Market value seems very high at the moment since there 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. I believe that person had damaged their CPU and/or PPU 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
After the fact, I feel like I didn't charge enough. I was trying to beat 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 and each modified N64 have 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