BB&B is a nice place for comforter shopping. But make sure you get to feel the comforter before taking it home. A good one will have, like you mentioned, a high thread count. A better one will have some weight to it.
My bed is done in microfiber (i.e. fake suede,) and I adore it. It's soft, expensive looking and machine washable. ALWAYS make sure the comforter is machine washable unless you have no problem dropping the $ to have it dry cleaned.
I got my set from
Women's Clothing including Swimwear, Shoes and Accessories at Spiegel.com. I've had it for maybe 9 years and it's still in fantastic shape. Looks brand new really.
Other places you can hit are department stores - I don't know what you have in your area - and discount linen stores. But imho, plan on spending some cash. You usually get what you pay for.
Good luck.