There are other 'advanced organic acid' coolants around (I think that's the correct name), but I'd rather you stayed with Toyota's SLLC. At 100,000 miles first change and subsequent 50,000 mile intervals it is not going to cost you an awful lot. Feel free however to save money by DIY engine oil and oil filter changes, and cabin air filter changes. Our friends at Toyota seem to bill heavily for these very simple tasks.