Haven't had to buy any. I have plenty of pants (& pants last for ages); bras is beginning to be an issue as the last lot I bought a couple of years ago & they're really not quite fitting any more. I was vaguely contemplating making my own (more for interest than anything else), but at some point reasonably soon I imagine I'll give up, go to Debenhams, & buy the customary 3 or so that fit & that I'm prepared to wear until they fall apart :)

Working in an office, IME, tends to lead to more clothes-shopping being required.