[srockets]

That $8k may cost another $5k to implement: current systems used by the would be employer may not be geared up to handle that non-standard asks.

[pdimitar]

Valuable counter-point, thanks. Still their problem though, and they should make it a bit more transparent: "It would cost us extra to implement this, are you OK with a final offer that's yours minus $3k to offset our costs?".