If you want the cheapest then youll have to wait for each to come to auction. Itll be a slow process. If you want to speed it up youll have to pay more.
There are some great websites out there which help with pricing. I like pokedata.io, and the owner of tcgfish.com is a member here as well. I’m sure there are others people prefer.
Pokemonprice is useful for psa cards. Generally you can just go off of sold ebay listings to get an idea for the average sale price, especially for things like base unlimited. It’s a skill you need to develop when buying or selling cards.
Ok well sold listings will get you an idea for what a card sells for an average. A specific seller can sell for whatever they want and disregard any sales prices if they choose to. If a card consistently sells for around 500 and the seller goes “idc, 700 take it or leave it” then its just up to you whether you want to buy the card given its sale history.
Im confused, on what you actually need help with? Im assuming you’ve looked at prices with the “prices all over the place” - the conservative price would be the lower end of the range…
& you can make a buy thread…read the rules but collectors dont typically sell for the low end
I’d look at eBay last solds to get the best estimate. If it’s low pop you’re either stuck waiting or going to have to overpay. Been on both sides of the situation as a buyer and seller.
IMO, average the last 3 sold listings for each card and tell the seller thats the price. If they don’t want to do it, walk away from the deal. While these are all amazing cards, they aren’t necessarily rare and you’ll have another opportunity to buy at that averaged price you found.