Yah!! Sounds like carb problems!! You can try a method called "Shotgunning" the carbs, which is described somewhere here on the site after inspecting the diaphragms. Yes, new plugs and wires, or at least new plugs should be in order. You should be getting over 200 miles to a tank of gas! Maybe the bike has an ignition issue and it has been running on only 3 cylinders since you bought it! They actually do run fairly well on 3...
Unfortunately yes, PROPERLY rebuilding the carbs is expensive, even if you do the work yourself! New parts alone run several hundred dollars, and properly reassembling them is an art form in itself just getting the throttles roughly bench sync'ed enough to get them running to properly sync'ed dynamically. You really need to use an exhaust gas sensor to properly set up the richness adjustment properly, or at least use a "Color tune" setup, but once the carbs are PROPERLY all balanced, it really turns these bikes on!!!
Sounds like you may have a plugged idle circuit jet on one or more carb's. Besides the main diaphragms, there are separate "little" diaphragms for the choke circuit that also may be an issue...