Your friend was correct in recommending NiMH rechargeables,
you can get a decent set of 4 and a charger for about
$10 if you look for sales. Never need to pay more than
about $15.

Please don't do that! Those cheap chargers are either constant current
or timer terminated. Pay somewhat more and you can charge your
batteries whenever you feel like it without worrying about state of
charge. Ray-o-vac has a good charger but, personally, I like the Maha
line. My 204 isn't as versatile as some of the newer ones but it works
well. I paid Cdn$30 for it a couple years ago.
For example, see
http://www.thomas-distributing.com/batteries.htm

Ted