Though I'd love to see a Chinese RF laser hit the market, I'm not holding my breath. Glass manufacturing equipment is a dime a dozen over there, so the tubes are common items... RF resonator setups, on the other hand, require some brains to design.
The 30W price seems a bit high to me (I would expect the price to be closer to the $4k-5k mark), but the 70W price looks quite attractive for the extra power. If those prices are for the entire machine and not just the laser, that would explain the extra dough for the 30W. Coherent makes some of the best RF, so if you get their warranty, I say it's a good deal.