I also have T8's. On my 3rd pair, and they are good, like you said, for several years. I think the bootie in the boots is what makes them so comfortable, and don't think the T3's have them. There was a member called "Alpinestars" and he had some Tech 8's that he sold from time to time. I think he worked at a bike shop and was getting good pricing because he had different sizes of new boots. I bought a pair of white ones from Motosport, but Black hold up better for the long life that they have.
You can get replacement soles and booties, to get you through until better times, too. By the way, my teammate bought some of the new tech 10's and they are not much better than 8's. The toe is like the 3's where they don't have the stapled steel plate. On those the sole wraps the toe. The buckles are new design on the 8's like the 10's. They are hard to snap if you have slack in it.