Terry, a tractor filter is no different than any other filter you'd find for a car or small truck, some auto parts stores will even carry some popular filters.
Now slightly off topic, but still talking about oil & filters. I use the highe priced filters & oil that I buy from my dealer; I know it is just plain old oil in a jug and probably just a WIX or FRAM filter with his brand sticker on it.
However, IF YOU EVER NEED SERVICE and you don't support your dealer, then you are creating a divide between yourself and your dealer for no reason. When/if you need your dealer, do you want him to think of you as that guy who raised the stink over the oil, or do you want him to think of you as that regular customer who buys all his fluids and filters here and supports his dealership?
I want the dealer to know me as a good guy. I want them go out of their way to take care of my tractor first, and better than they take care of you & your tractor. I want to be at the front of the line when it comes to customer service. So I pay the extra $1 a gallon for oil instead of buying it at Wally World and I pay the extra $0.85 for a filter. But the service guy sees his brand of filter on my tractor, and the parts guy sees my face every once in a while, heck I even say HI to the sales guys when I stop in. And so far, it seems to work to save me a lot of money on other things.
When I wanted to add a MMM they beat the best price I found from a well known low priced internet source by HUNDREDS of $$$, and they picked up my tractor, installed it, and returned for the quoted price. And when I wanted a snow blower, they beat another well known low priced internet dealer by $200 (plus shipping costs), they even cut the PTO shaft to fit, and delivered it to the back of my tractor for that price, on the exact same model.
Honestly you will change your fluids and filters one or two times a year. The price difference, over the course of a year may be $5 or $10 more to do it the way I do it. I consider it an investment.