Welcome to AF.
Thier are a few places to find Alero products,
though the list gets smaller everyday.
Here are a few;
PFYC
http://www.customautoaccents.com/products.html
http://www.andysautosport.com/oldsmobile/1999_9999_alero/
Not exactly sure what your HVAC head unit looks like,
but some other N-body overlays might work.
Might also try a google search or Ebay
for gauge or dash overlays .
Hope that helps.