Thanks for all the suggestions... hard to make a decision here.
My top budget would be in the price range of ~$40 per cap, which is already really pushing it as the entire build is not that high end.
@cal3713 thanks for the offer but those are way over my price range. (probably even at used price). they are also quite big, not sure if they would fit.
@terry9 the MIT RTX look reasonably priced at around $25 a cap, I'll take a loopk. The RelCap TFT's are too expensive at over $100 per cap.
@erik_squires @hifijunky will take an additional look at those MR/CMR's
@motokokusanagi
the design is the RJM Sapphire v4. I participate in the build thread in DIY audio but most members there experimented with limited types of caps. My first choice (the Mundorf) was based on impressions there. Agreed that I don't have good evidence.. none the less am interested to try something else, which I could then compare to my current amp and see the if capacitor has the effect or not