I think even less for Gaslight, with patience more like $25-30.
Agree on Countdown - it's pricey, and is routinely $100+.
4E is not really special - $5-15 probably.
Areas of interest/knowledge: Harn, Pendragon, WFRP, Ars Magica, anything BRP based, CoC, Runequest
Planning: BRP/Harn