To save money, try your local salvage yard. They may have ones that are from a newer vehicle that will fit and cost less than brand new ones. You could possibly order oem style ones from a dealer but the will cost a lot.
The best place to look for new seats for your truck is online. Search on google and type in your truck make and model and new seats next to your model. You will find the best and lowest price for new seats.
Well if you want oem style seat you can either contact a dealer for new ones or a junkyard for used ones. If you just want some seat you can look for aftermarket ones. There are lots of websites and catalog where you can buy these.
You can contact the dealer or go to the internet and type in the make and model of the truck and ask for seat information. Sometimes Ebay has truck seats for sale.
Many auto stores and online companies usually provide fair prices for truck seats, as well as seats for a multitude of other vehicles. Used auto parts stores can also offer this product, possibly for a lower cost.