You don't HAVE to have a pad with shim pockets to use shims.
I have used quite a few shims without any pockets. Balance shims, some from Schneiders, I think I have a pair of Cashel shims too.
The only trouble I could see is if you're using them right at the back - those would need pockets or velcro.
Agree completely re: not having to have a shimmable pad to use shims. I've known people who duct tape the shims to their regular saddle pad--or just slide the shim into place before each ride.
If you're using the shims right at the back, you could use the Shimz stick-ons from RiderGrip. I've not tried them myself but it seems they wouldn't be any worse for your saddle fit than the shims used in shimmable correction pads: http://ridergrip.com/
If it's gotta be a shimmable PAD, though, some of the cheaper options on the market are ECP Correction Half Pad (about $135, Sheepskin) or the Thinline Trifecta Cotton Half Pad (about $130).
Yup, I'll also put a word in for just sliding the shims in on between the regular pad and the saddle. I went the first time I saw my trainer do it, but they stay in once they're in place, you just have to remember they're there when you untack!
I am thinking about a saddle pad on tackaholic.net that is around $59.00 or so (I think they call it a PRI nytro gel pad. Got a dressage one on ebay from them last year, but was looking for a jumping one. The shims aren't terribly thick, and I think one could add some extra padding in there.
Anyway, that's about the only cheaper one I've found. The pad I got fit one of the horses, the other one needs a bit more padding.
How about buying two cheaper pads and sewing them together along the all the outside edges, cut holes along the spine (where shims will be go in), put in shims and sew around 3/4's of the shim. Don't sew the shims in, just outline their shape so the shim will sit where you want.
I don't sew, but I don't think it would be hard.
Thinline has shimmable pads that are not bulky. I have the non sheepskin Trifecta, but they are on the pricier side.
I've been all over the place with this issue, including the duct taped home made shims on regular square pads. Right now I'm trying out an Acavallo Gel Wither pad that should be very versatile and go with any regular pad, including shaped fleece for show. I just have to trim it down a little as it's made to fill deeper pockets behind the withers than my horse has now.
Wow - you guys are awesome. Love these ideas, especially ducktape, velcro, and the $24 half pad from Schneiders. (I admit I did think of gluing the shims on, too, although I don't know what sort of glue wouldn't leave a hardened lump...)
I know I'm a little obsessive here, but I tried attaching velcro patches to my square pad and to some home made shims (some extra memory foam from another pad). I guess I'm looking for more simplicity, something to just slap on and go. If the Acavallo pad works out, we have a winner! (Thinline is just too big for my saddle)
I made a shimmable pad out of an old fleece gel pad cover, some memory foam from an old mattress pad, and nylon strapping. Took about 10 minutes to cut everything and hand sew some nylon billet loops on. I put the shims (rear in my case) in the cover and sewed a pocket around them. Initial cost = $8. I got some "fancy" Fleeceworks memory foam shims a little later for $20 extra.
The best part is that the fleece cover has a Beval tag, so it looks pretty legit and not nearly as redneck as it sounds!