Funds are fine, but there's way too much science. If I wanted to play it safe I could probably build up a good amount of funds, but a few disastrous bits of R&D will bring it back down pretty quick. I've never done any boring contracts just to get money. Technology advances are way too fast though. You can easily launch the first Duna mission you do with nuclear engines or other advanced technology, which is a bit of a shame. I feel you should have to try and scrape through with crappy technology for a bit longer before being able to access that sort of stuff.