life after 300K?
Your first expensive is replacing all of the fluids-if needed. Outside of that, your Supplemental Accessory Driveshaft (or SADS for short) bushings will go bad. The dealer will tell you to replace the entire shaft at the tune of $1000+. Don't do it. Just get the bushings replaced. the bushings alone are around $250. From my experience, this is one of those items where the Genuine Toyota parts are the best. It shouldn't cost you more than $500 (extreme worst case scenario) to replace them.
Search Toyota Previa Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Toyota Previa Experts