retail price will always be the same for the game. buy used game if u want to save cost.

new releases game, price wise most of the time same price with physical copy. overtime, online one will become cheaper.

any game shop will do tbh, price for game didn't vary that much from shop to shop. almost all shop selling at retail price unless there's a promo.

never encounter problem with used game before. yes, do check for scratches. minor one should be ok.