Which trainer do you have @Adrian? I'm tempted by the wahoo kickr but finding out difficult to justify the cost!
I bought my Elite qubo fluid from ebay for about £90 last year, and other than having to get a new rear tyre, there has been no additional costings.
With regards to the boredom side of things...
If you use the Trainer Road app, you can do their workouts and watch / other apps in the foreground - i.e. netflix etc...
With Zwift - there isn't any boredom as you are riding with other virtual riders and the amount you move on the screen is directly controlled by your riding.
Currently I'm mainly using the Sufferfest Videos / app - which is great as you are immersed in the footage from real races and that combined with the sound track and how they set up the videos makes for a very immersive experience. - Plus it's bloody hard, so you've not got time to be bored!
I'd say go for it for £30 @CRS1965 - worst case, you can put it on ebay in a few weeks time if you don't get on with it.
Both Zwift and the Sufferfet apps have a free 7 day trial, so should be long enough to gauge how you like them.
Best bit of advice I can give you is Buy a Fan!