Just my 2c, but i stay away from bottom shelf stuff. Yeah that MAY protect you well enough for one crash, but in general, the cheaper stuff is "one crash" suits. Don't corner yourself into one brand, and look into quality stuff. (Alpinestar, spidi, dainese, etc) and plan on spending more than $1000 for their better stuff, don't go entry-level on your self-protection.
As mentioned, if ultimately you think you'll end up on a road course, one-piece is the way to go. I'd much rather find a good used suit that may have some rash than buy a brand new cheap suit that probably won't withstand a simple lowside slide.
Personal experience: bought a $700 arlen ness on sale for $400, lowsided at approx 70 mph and slid for a ways, was totally uninjured, but the suit blew out several seams (which could have been bad). So i paid 400 for a suit i only wore a handful of times. My buddy who races, spidi suit for approx $1600, crashed several times, some pretty good ones, and has been wearing his for years, no damage but cosmetic scuffs/rash.
The moral, buy quality stuff. If you don't have enough, save a longer.