I think it could be done. They'd have to be very smart about it, but it's possible. You're obviously not going to get the quality of effects from the movies but it's definitely possible.
Only Reed and Johnny would have the expensive effects. They've been doing invisible man/woman stuff for ages on TV, and with the Thing already being in a rubber suit for the movies, no reason they couldn't continue. Heck, even in the Roger Corman low budget FF, the Thing looked pretty good.
The most expensive thing on a TV show is building the sets, well if you have a fixed Baxter Building set, that will be used over and over, you can really lower your production cost.
You also have to have a talented group of writers, that can throw in the occasional script that doesn't have alot of effects, but can still deliver.