IMO, eyepieces with >65 degree AFOV are a category where the inexpensive ones are really only "fair" in performance, possibly up to the "good-ish" category but only with specific focal lengths. So the upshot is, once you get them they will seem "ok" but then after some time you will become more and more aware of their shortcomings and want something better...especially after you have looked thru something better!
Now true, the focal lengths of your refractors are comfortably long at f/8 and f/10 so the lesser eyepieces will perform better than they are usually given credit for. But there are other issues with the less expensive ones besides just how well the off-axis is. The multicoatings are usually not a good and neither is the interior baffling and light suppression so more likely to get ghosts or flare or even edge-of-field-brightening so the views just do not look as starkly nice many times. So what I am saying is that if you really want 68-70 degree eyepieces the minimum you should be looking at for solidly very good performance would the Explore Scientific 68 Series. So that would be the starting point IMO for a set 68 degree "complete and usable set" as you say.
What I would encourage you to do is to have some patience because the $60 Paradigms or BST Starguiders, which are 60 degree eyepieces, are incredibly strong performers at their price point -- so much so that they really quite satisfying in every way with nice small form factor, comfortably long-ish eye relief, nice ergonomics with their rubberized housing and adjustable eye guard, and a great view with good contrast. I mean I have premium eyepieces like Pentax XWs, Baader Morpheus, and had TV Naglers, but even with those class of eyepieces many times I find myself just picking up the BST Starguiders as they work so good that I feel I am missing nothing except the slightly smaller AFOV of 60 degrees, which still feels generous. I even did recently some direct compares on performance on nebula looking at contrast and bringing in the faintest portions as well as internal details of nebula of the BSTs with my premiums, and really they were just as satisfying.
So I would recommend that if you really want to keep costs down, then get the 18, 12, 8, and even 5mm BSTs or Paradigms and they will work simply fantastic in your f/8 and f/10 scopes. If you wanted to get a longer focal length then my recommendation would be to go with the 24mm ES68 ($189) or the 24mm APM UFF ($199), the latter having more comfortable eye relief but with a bit larger form factor. When one gets down to the longer focal lengths, the complexity of the optical design needs to be more to handle the 60 degree or greater AFOV so for this focal length you really want to spend a little more money.
Hope this helps.