new control arm bushings?

[aussie 540i]

still strolling through ebay and was wondering if i could have some advise on whether the following item would be a worthy investment, my 1993 540ia (we only got 70 manuals in 1994, and i still cant find one..lol) she has done 120,000 kilometres, is totally original and stock standard (but seriously considering a fat chip once i save up the funds ....lol) she runs very smoothly on the road but (she is 11 years old and untouched bar maintence) we do get a "bottom out" sensation in the back if i go over a fair size "bump" in the road, otherwise she is "as smooth as". i do not (think) that i have self-levelling rear suspension, if that helps, would appreciate your valuable comments.

here they are:

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7910731165&category=33583

thanks