Market value seems very high at the moment since the supply for Hi-Def NES and UltraHDMI have dried up. I think my brother and I are the only installers that have any kits on-hand. If supply ever comes back to satisfy demand, then prices can normalize.
I bought the last 4 kits ever sold from the source (game-tech.us) over 1 month ago. I have 1 of them up for sale on eBay (
link) and I'm still sitting on another.
I also bought someone's failed install attempt on eBay -- an NES board with soldered interposers and a Hi-Def NES board, but no CPU or PPU chips to go in the interposers. My brother put another CPU and PPU in and it works fine. It's possible that person's CPU and/or PPU was bad, or was damaged when attempting to desolder them (the most difficult part of the install if you don't have the correct equipment).
Jason Rausch of Game-Tech.us (the only source for Hi-Def NES kits) said in a recent interview that Kevin "Kevtris" Horton (brilliant creator of Hi-Def NES, Jason's business partner) is occupied by a contract job with an NDA clause. He said the next manufacturing run of Hi-Def NES isn't even on the radar. My last kits will probably go on eBay as auction format to see what the current market value really is.
The kits I have sold recently:
$190 for Hi-Def NES kit + installation (NintendoAge member Tbone sent his NES to me)
http://nintendoage.com/forum/messageview.cfm?catid=56&threadid=176506
In hindsight, I probably didn't charge enough. Beating the price of established modders, but I have been the only one with any kits at all for a while now.
Used a red board from my previous order.
$345.00 for NES-101 top loader with Hi-Def NES kit installed (eBay fixed-price listing)
http://www.ebay.com/itm/132312643371
Used one of my yellow boards from the most recent order.
[traded kit+install for some gaming stuff] (NintendoAge member A2600 sent his NES to me)
http://nintendoage.com/forum/messageview.cfm?StartRow=1&catid=5&threadid=176458
Used a red board from my previous order.
$380.00 for NES-101 top loader with Hi-Def NES kit installed (eBay fixed-price listing)
http://www.ebay.com/itm/132273148763
Per buyer's request, I ended up using one of my yellow boards from the most recent order instead of the red one pictured.
I've been focusing more on UltraHDMI for N64. I got the last 21 of those kits. Each modified N64 has been selling for >$400 within hours of going on sale. I'm finally testing an auction format to figure out what it's really worth (
link). I really like this one and would love to keep it for myself
https://imgur.com/a/Lc1xB