Necessary to use new nuts on refitting?

I have an audi a6 2.5TDi Quattro 1996 and my haynes manuel says i need to use new nuts when refitting my front anti roll bar with new bushes (obviously i have to take the originals off when replacing the bushes). But all the local parts people either don't have them or don't have sets to hand ( i need ot large ones for the outer ones and 4 for the inner bushes bracket) and have seemed surprised and said no one seems to be asking for them so it can't be necessary....but haynes says....|||they are lock nuts and should not be reused but if you cant find new ones put lock tight on the old ones,auto store can sell you some|||the nuts are milimetric ones, and siince iso norms exist, you can buy them in any hardware store that sells milimetric nuts and bolts, take de nuts with you to get de some ones.