At that price, you have plenty of options. If you live somewhere where FJ cruiser lockers are plentiful and want to DIY it, go that route (and tell me where you are so can get one lol). Your other choices on that budget are ARB or an Eaton E-locker if you remove the third member yourself and then take it to a shop for the locker install. I've also read lots of really nice things about the Detroit TruTrac on our rigs, as it apparently really compliments ATRAC.
For my 0.02$, I would go with the Eaton E-locker, as its new vs the FJ-Cruiser locker of unknown vintage. When I priced it out, it was 1100$ for the e-locker, and 250 for install. Leaves you 150 for buttons and wiring. I prefer that over the ARB just because air lines make me nervous for no good reason.