I bought a touring bike in 1991 that had biopace, promptly had a knee problem that was probably a combination of too much weight on my bike on a rather tough trip with terrible hills and/or the biopace.
read and heard after that knee problems were associated with it, more when one would pedal with a fast cadence, or revolution your feet are turning.
I changed them and am glad I did, the regular round chainrings just felt more natural and my knee was happy again.
chainrings shouldnt be too expensive, shop around as they can range from cheap to outrageously expensive. Id visit a few bike stores toget an idea of wht is available for that crank. take a look at your crank and you may see that with an allen key of proper size, you may well be able to change them yourself without having the crank taken off. If it need tobe taken off, and want to learn todo it, a crank puller tool is easy to use , probably pretty cheap , i bought mine so long ago I have no idea how much it was.
in any case, should be a cheap switch, maybe 20-30 bucks for two chainrings. but get an idea at a proper shop.
dont know how much you ride, but biopace came and went the way of the dodo because of the weirdness it caused for knees. read up on it if you want to get more opinions.