Kito,
Check out Marine & RV Direct on eBay:
http://stores.ebay.com/Marine-and-RV-Direct
I bought a complete 3 bow bimini from them with 1" tubing, boot, and the optional rear support poles for $89 shipped. The quality is very good for the price and their shipping is fast. I'd buy from them again.
Size depends on where you want to mount it, on the gunwales or on the deck outboard of the gunwales. I bought mine taller than the average C22 bimini and cut it down for a custom fit under the boom that lets me stand up under it. The CD bimini is too short for that. I also put it on tracks outboard of the gunwales, which gives me three usable positions: folded up aft out of the way for boarding and loading (but in the way of the winches for sailing), middle of the track for sailing (main sheet and backstay clear), and forward either raised to cover the open hatch at night for stargazing or laid down on the cabin roof completely out of the way for a clear cockpit.
I'm pretty happy with it. I'll be putting a post with all the details on my blog soon. I don't have any pics yet, but if you have any specific questions, I'd be happy to answer what I can.