I would only recommend getting good tatami mats. I know they are pricey, but they are 100x better than those crappy puzzle mats that so many dojo use. Those mats are notorious for getting your toes caught and ripping the skin off your body. Personally I don't understand why any dojo would use them, especially for BJJ. It's not wonder so many BJJ guys get staph infections.My recommendation
Enough of my rant, back to tatami mats. These are the green mats that you see in most judo dojo. They are (very) expensive (I guess it depends on your budget). However, I was able to get 4 mats (they are about 6 x 2 feet each) for free from my gym. My gym replaces the mats every so often, so I just asked the manager if I could have any of the old ones that they were going to throw out. They aren't in great shape, but after a cleaning, they serve their purpose.
So all you have to do is go around to any local dojo, gym or school that might have these mats and ask them if they plan on replacing their mats soon and ask if you can have or buy some of their old ones. Some places might not have thought of replacing them, but change their mind given the opportunity to move the old ones.
A cheaper alternative to tatami mats are the blue folding mats that a lot of schools use for gymnastics or wrestling. However, I would highly recommend the tatami mats since they absorb shock a lot better than any others.