This may not be directly applicable since I bought a new frame too (I wanted a longer top than the original one).
I used
https://www.boatcoversdirect.com/ and asked for the THT discount which got me 5% or 10% off the lowest price I could find online.
I got the Carver 4A5487UB which fits the V20 nice if you want a 4 bow 8' long top.