the best free limiter is BuzMaxi3: for high transparent loudness. And the NastyVSD (within Nasty Series): as a vintage maximizer. Barricade is also very good. I use the old Voxengo Elephant (cause their new graphic style has nothing to do with voxengo-Plugins anymore), but if you like the GUI, they offer discounts at the moment. With this one, you can definitely save your money for L2. But as a Reaper user, its just fair to say, that you can use the Reaper limiters of course, but i would work with the Freeware named above instead.