Run a search for "beginner cad" within this forum. It's a common topic and you'll get a lot of useful info.

As for cost I doubt you'll beat the non current versions of TurboCAD selling on Ebay for typically $20 to $25 delivered to you. Look for versions from 9 up to 12. Any of these will easily serve your needs for years to come. However be sure to go for the Deluxe version and not the Designer version. Designer is very limited in a lot of file formats it'll handle and isn't worth your time.