My computer broke down and I am interested in buying a used or new
computer, or information where used computers on which windows 98 can
be insalled, can be bought.
I am looking for a computer with floppies a: and b:, cdrom, bays for
accomodating the 2 hard disks which were in my broken computer and the
ability to connect to a printer.

Have you looked in 
http://www.ebay.com

You can find all types of computers, brands, and models.

I would check with Newegg.com

I would personally recommend buying a new computer. When pricing older
computers it seems that after shipping your still looking at atleast
$100 , why not buy a new low level computer for a lil more. It will
come with windows xp but since you already have an extra harddriv eyou
can install win98 on that harddrive and have a dual-boot system.
Im sure you will enjoy all the extra functionality of an XP machine.
Cheers

Windows XP is an incredible operating system, it's very stable and
virtually never locks up. It also has a cool feature called "CLASSIC
VIEW" which makes it LOOK exactly like Windows 98.  My advice is to
give it a try.