Do you know what brand you have currently in the yellow? Definitely check out your local Habitat Restore shop and any other shops that deal in new & used building supplies. Have you tried eBay? Here's a few listings I found...

http://www.ebay.com/itm/American-Standard-F-4043-F4043-3-5-toilet-vintage-BRIGHT-LIGHT-SAFRON-YELLOW-/400259814765?pt=LH_DefaultDomain_0amp;hash=item5d3158156d

http://www.ebay.com/itm/Kohler-toilet-3-5-gallon-vintage-retro-antique-yellow-/260967299623?pt=LH_DefaultDomain_0amp;hash=item3cc2dcfa27

http://www.ebay.com/itm/Crane-toilet-tank-N550-Sr-lid-N-550-548-AZTEC-GOLD-GOLDEN-YELLOW-HARVEST-/370199402106?pt=LH_DefaultDomain_0amp;hash=item56319a967a

http://www.ebay.com/itm/Eljer-toilet-tank-99-31R-5120-99-lid-1939-PALE-YELLOW-/370086759379?pt=LH_DefaultDomain_0amp;hash=item562ae3cbd3

I came across this web site last week while looking for pictures of vintage baths. This guy may be able to help you with a source. Wonderful website!

Here is a link that might be useful: vintageplumbing.com

Thank you mydreamhome for the suggestions. I don't know if I have a Habitat for Humanity but will look into it. Since the toilet is long gone I don't know if the tub or sink have any markings but I'll check it. It's not a bright yellow and not a dark gold yellow but somewhere in between! Seems a bit gross looking/talking about old toilets but that's what bleach is for!

DebraV, I checked that web site and WOW. I love Victorian stylings but have never seen such ornate fixtures before! I'll contact them. Thanks for posting!