As has been stated above, you get what you pay for. I bought an 16' RMR last fall. I've had her on one trip, in which I also had my 1st pin in rapid 15.
The pin was not the boat's fault, but it did expose some weaknesses. During my wrap a D-ring blew and allowed the frame to shift slamming the dry box into the tube and puncturing the tube. The punctured tube also happened to be the tube that was holding the boat on the rock so the boat was then able to come off on it's own, earning her the name Lucky 15.
As for exposed weaknesses: (1) the D-rings are very beefy and welded on, but the are only welded in a 3/4" perimeter of the d-ring patch. This is definitely not as strong as having the entire d-ring area glued down. (2) the material on my boat is not very thick, I don't know what denier really means, but my boat's material is about 1/2-3/4mm thick. Maybe 1mm. The boat weighs something like 185 lb. 16' NRS Expedition rafts weigh 10 lb. less, and definitely have thicker material.
All that said, do I think that my boat is a bad boat? Hell no!!! We have history now, i love Lucky 15. And I'm sure that as long as I take care of her, she will take care of me.
So go buy the boat you can afford, it'll get you on the water and you'll be able to upgrade someday if you need to.
Besides, I'm glad the d-ring blew and popped a hole. That alone allowed my boat to come off the rock without us having to set up a potentially difficult and dangerous Z-drag. here's a pic of the pin, the yellow dry bag up front is holding 2 30racks of PBR, I'm glad I rigged her tight.