Templebody - first off - YAY. Good for you for going down in weight enough to need new clothes, as annoying as that can be! If it's band size on the exercise bra, can you sew? Would it work to fold over a bit of the band and sew a line of stitches close to each end of the fold? I haven't tried this, but it seems to me it might work.
As for exercise clothing, I've found some nice stuff at Tuesday Morning and TJ Maxx lately, and once I found a brand and a size that seems to work for me I actually have bought stuff on eBay. Much of it new, with tags still attached. Wait for the auctions (instead of Buy it Now), and check out what sniping is (auctionsniper.com is my favorite) to get stuff at the lowest price. I've been spending perhaps 20-30% of retail lately to replace my wardrobe - both work and exercise. For exercise I've been falling in love with Marika stuff. About $15-20 per piece at the stores named above, some neat compression-y tank tops with built in shelf bras, plus some really pretty yoga-style pants with legs that are flared at the bottom (plus neat scroll designs on the leg, or waist bands that match the tops.) My theory - if you love your exercise clothes enough to want to wear them, you'll wear them more. And you can't just put on your exercise clothes and not work out, can you?
Hope that helps!