loading the model would be similar vram footprint, correct, however the size of KV is based on 'active' params, not total params. So while at 1k ctx both will be in the same ballpark vram footprint-wise, at 100k the story will be very different. 27B at q4 kv for 256k takes ~8gb, while 35B at q4 kv around ~3.5gb, so at full precision kv those would be ~32gb and ~14gb (all ballparks, if you want exact numbers, its not hard to test).

As for the "cost", here i think the interesting arguments are around speed vs accuracy/"getting the job done", not literal $ cost per token.