I agree, one may start out on the free version, learn the program and, if it appears to work out, switch to the paid version and gain a few extras. I've been working with it for months now and it does everything I want it to do.Hi.
I don't know how 'professional' this program - that I am about to mention - might be considered to be, but it certainly is well-heeled, and also VERY cost effective (free). The name of this program is Google Sketchup. I am getting my feet wet with it, and really loving it. You may want to give it a shot, as it could very well be something quite workable for you. I find that I (also a woodworker) need no other program for my product design efforts.