Just nab one of the Briefcase combos off the West Exit.You does not charge a arm and a leg,and he usually has good condition decks for sale.His pcengine prices are good too.
You really would be fine just playing PcEngine games,the TG side was not all that exciting except on some of the cd titles like Exile or Ys Book1&2.
With a Pc Engine and Cdrom add-on you could nab a Arcade Card Pro or System 3.0 card very cheap,much cheaper then trying to buy a US System 3.0 card.
If you like fighting games the ports of World Heroes 2,Fatal Fury Special,and Art of Fighting are extremely close to Neo quality for the Arcade Card Pro,and do not really require a 6 button game pad to play if your on the cheap...
The arcade ports for PcEngine hucard or cd wise tend to stomp the shit outta the Super Famicom/Snes/Mega Drive/Genesis/Master system ports.
Forgotten Worlds,Buster Bros,Sf 2 Champion Edition,the NeoGeo ports,Chase HQ,SCI,Aero Blasters,Raiden,Zero Wing,R-Type,Tiger Road,Cadash,HellFire,Gradius,Gradius 2,Salamander,Ninja Spirit ect....are all good games,consider must buys if you love arcade games.