At my iPhone's suggestion (photo at right), I decided to spend a couple hours looking around for pony play gear. A consolidated list seems in order since my ponyplay links page is becoming a little crowded, so I will do a few posts on where to get ponyplay gear.
Today's topic: bridles. I am only including links to purpose made bridles and head harnesses for ponyplay since bit gags and bit gag trainers are fairly widely available. This list is in no particular order:
Fury Fantasy - They have a few different bridle designs, all of which look to be able to accommodate your choice of bit. Pony ears are available on the bridles. I really love their gear.
Restriction Wear - They have a few styles of bridles, with many colors and color schemes to choose from. It's really worth a look - ever wanted a pink bridle with pink bit? They have it.
Sinvention - They sell a few different designs. I like the look of their gear, but most of their head harnesses do not allow you to directly attach a bit, thus they are more like halters than bridles. Still, I love their gear, and you can wear a bit gag over top of most of their bridles.
Fleet Ilya - Really more of a bit gag with reins, but it matches their saddle. They also recently added a bunch of new pony gear (and other animal play items) including this bridle with ears and this one with integrated gag and removable blindfold.
Marquis - A nice bridle with ears that is available in either vinyl or leather.
Fantasy Leather - They have a couple bridles for pony play. The Deluxe pony play bridle offers a removable bit - potentially you could then have your choice of bits depending on how (dis-)obedient your pony is on any given day.
S-Art - A couple nice bridles: one made with brass and leather that comes with plume and mane (third down on page) and another more elaborate bridle (sixth down).
Fetish Universe - They sell four nice bridles (top left, and then second and third rows on the page): all four come with pony ears and two include blinders as well.
Native American Exotics - The sell a few bridles, designed specifically for Western style ponyplay. Their bridles are beautifully crafted.
The Stockroom - Not sure who makes this one since I've seen it around on a few online stores, but I've linked to The Stockroom's pony head bridle set, which comes with pony ears, muzzle, blindfold, and blinders. It's actually a really hot looking bridle.
Terginum - They have a nice pony play bridle, which comes with pony ears and blinders. It looks well crafted and from the photos, it looks like it can properly attach a Pelham or curb bit.
Fetters - Their deluxe pony bridle has beautiful red piping on the blinders, and the bit is interchangeable, which gives you versatility in training your pony. They also have a standard bridle that comes with pony ears (you cannot change the bit in the standard bridle).
Firebird Leather - A good looking bridle with a gorgeous mane. They have lots of color options.
Spanking Good - They sell a couple bridles in addition to a headpiece (which may be a halter or a bridle, but I cannot say for sure from the photos). I rather like their headpiece, which has a nice browband design and large blinders (good for keeping a pony focused).
Bridled Desires (formerly Abigails Stable) - They sell several beautiful bridles including one complete with mane, plume, blinders, and ears (and your choice of bit). It is available in various colors, and it does look pretty cool with the feather plume. Edit: They are no longer selling pony play items.
Heavy Rubber Shop - A cool looking rubber pony bridle with ears and blinders. It would be an especially great bridle for a rubber pony.
Extreme Restraints - A bronze, metallic cage style head harness with plume. I can't tell if it can accomodate a bit or not, but if so, it might make a nice in hand bridle for show ponies. Edit: They are no longer selling the bridle.
Zado - Cool looking bridle with ears, reins, and an integrated metal bit (the description says the bit is plastic covered). Edit: They appear to have discontinued the bridle.
Fetish Discount - They have regular and deluxe pony bridles. Both come with plumes (available in different colors), reins, and integrated bit. The deluxe version also includes blinders and ears.
Fetleather - The bridle is available in several colors with either brass or chromed metal fittings. The bridle has a slight visor above the eyes similar to one I saw in some early ponygirl photos (the name of the series escapes me at the moment). Sadly they have discontinued the version with the ostrich feather plume, but it's still a great looking bridle. The shop also sells a few other pony items.
Stormy Leather - A nice leather bridle that comes with detachable blinders and reins. This one holds a special place in my heart as the very first piece of human pony gear (and actually, also the first piece of bondage gear) that I bought. It's pretty cool that they're still making it more than 15 years later. Update: They stopped making this bridle after merging with Stockroom, but you can see how it looked via the internet archive.
Birch Place Shop - A pink bridle complete with pink ears and bit, their bridle is sure to be a show stopper.
Honour - A pretty bridle with striking red ears and plume.
Leather Etc - The have a couple bridles in different colors with and without blinders. They also have leather wrapped bits in cool colors.
Wolf Princess Designs - I am not sure if they are taking orders at the moment (they do custom work for the most part), but I've seen their custom made bridles in the past, and they are quite stunning.
That's it for now. I'll try this again for another piece of tack at a later date. Hopefully this will be of some use to you in finding a bridle for you or your pony.
I'm sure there are a few other places to buy bridles, but these are the main ones I know of. Please let me know of any other bridle retailers, and I'll be happy to put them up on the list.