That response isn't bad for an in-room response. The ragged low end is expected, and you would benefit from some EQing there. The dip at 90 Hz may mean the subwoofer is not fully in phase with the speakers. I would guess that the dip at 1.6 kHz would be due to the angle you are listening to the speakers at, and is probably due to some slight cancellation effect of the woofer and tweeter overlapping each other, since the crossover is at the same area (1,500 Hz). This can also be seen on
this graph, where the purple trace is the RB-62 IIs. Some of the character of that measurement can be seen in your measurement.
Anyway, I do think you could benefit from a more neutral speaker. A speaker with a flat response could shore up the dips at 500 Hz and 1500 Hz, and these are pretty crucial frequency ranges. I think you should get something to trim that peak at 70 Hz. If you do that, you will have a very good subwoofer response for a single sub in a small room. It doesn't dig deep, but upper 30's Hz response should cover almost all conventional music recordings. I wouldn't bother adding another sub, as long as you get the speaker in synch with the sub to shore up that dip at 90 Hz.
It will not take $3k to fix these problems, although that is a nice healthy budget.