HAHAHA um try a junk yard or a Supra with a salvage title for that price range. You'll be very lucky to find a Supra with a clean title and decently low miles for $21k, unless it's a NA. Rarity/demand for a mkiv plays a big role in the price of Supras in different areas. For instance, where I live, Supras that are sold in car dealerships go for around $45k. Twin Turbos hold their value. You will find some twin turbos on websites such as EBAY or autotrader.com for less than 15k. Beware, almost all of these Supras are scams. Oh and they didn't make a factory yellow for a mkiv.
www.mkiv.com is a good website to learn more about it and they have some for sale every now and then. Good luck.