First question: "where to get a PCB without removing the ROMs from an existing game"-
Depends on the specific Castlevania hack.
If it's based on CV1, you can get UNROM reproduction hardware from several places, including
INL,
retrostage.
If it's based on CV2, currently INL's MMC1 reproduction is out of stock, but
retrostage still has something. Unless you're specifically looking at bisqwit's
retranslation, in which case all this advice is irrelevant.
If it's based on CV3, you're mostly out of luck; there's no reproduction MMC5 or VRC6 available.
Second question (in the subject): "where to get the right ROMs"-
This is only relevant if you're buying from retrostage or scavenging parts from an existing PCB. With INL's board you should use his Kazoo programmer.
I'm partial to using all new flash EEPROMs, like the SST39SF0x0 parts. You can buy them from
Microchip directly; they're usually cheaper than any of the electronics supplies distributors. Make sure you buy the DIP one of the size you need.
You'll also need a programmer. The cheapest options seem to be the MiniPro USB programmer and the Willem parallel port programmer.