If you are heading down that path anyway, a m³ is good practice, with a STEPS PSU... and can be done for about $250 if you are a good parts shopper, and less if you have a good surplus electronics store nearby. Plus, there are build threads, and copious amounts of build directions on Ti's site (amb.org). I built two as my second ever projects, but are tough enough to get you geared up for the beta.
Oh, for reference, I built the m³ BEFORE cmoy (why bother), and MINT (disaster, as I can't solder smd). Just depends on your level of motivation, ability to read / follow directions, and threshhold for pain. It will get you better prepared for what is coming, and the basic topology of Ti's designs. Further, if you can't do a m³, do NOT bother chasing the dragon of beta22.