Just looked up the price on another board and the price is 1.5million bells. It's Shop and Service board.
Maybe an auction with a starting price and buyout price would help.
I bought mine for 20 million but that was in the first year when it was hard to get.
if you're looking for tbt, i remember they were wroth 100-120 tbt and for IGB, they were worth 1m bells and more. that was of course last time. i havent been visiting the retail section so idk whats the rate now but i think its still the same?