Looking for an online retailer (of reputable quality) who sells a
128MB RAM upgrade for my fairly old Toshiba Satellite 335 laptop.  Any
retailer submitted must have prices posted, as well as the product
being in either "new in box" condition, or with a good replacement and
DOA warrenty if used and the item must be in stock.

I only add these conditions as most of the places I find that still
have the part listed, no longer carry the item in actuality when I
contact them.

The brand of the RAM doesn't matter too much, however if it's a good,
recognizable brand I might add in a tip.

As of today, there is at least one piece of used memory available.  

Crucial.com offers 144 pin SO-DIMM modules for this laptop.  Crucial
is pretty much always right.  However, the max they offer is 64 MB. 
Thus, we'll work on the assumption that it is a 144 pin SO-DIMM.

Toshiba specifications state that it is a 66 Mhz databus, so any PC-66
or PC-100 memory should function in it.  So, let's try to find some
144 pin SO-DIMMS:

Pricewatch points to Compgeeks as having a 128 MB PC100 SO-DIMM
module, which should work with the Toshiba laptop.  The Toshiba
website does not specify the formfactor of the memory, although
Crucial indicates it is SO-DIMM.

Compgeeks Memory:
http://www.compgeeks.com/details.asp?invtid=16X64NB100&sourceid=00405235678414795940

Pricewatch search for Used 128 notebook memory:
http://castle.pricewatch.com/search/searchmc.idq?cr=Used%20128&qc=%22USED%22*%20AND%20%22128%22*%20AND%20%40totalcost%3E0%20AND%20%40minorder=1+AND+%40ctd+281&i=281&ct=NEN&c=NEN-Notebook%20Memory&mi=N&m=N&ne=13620&l=13574

Toshiba User Guide (self extracting executable file)
http://cdgenp01.csd.toshiba.com/content/support/downloads/330guide.exe

Toshiba Specifications:
http://www.csd.toshiba.com/cgi-bin/tais/su/su_sc_outFrm.jsp?moid=1073769722&ct=DS&BV_SessionID=@@@@1416580255.1058812403@@@@&BV_EngineID=cccjadcilkkdmlkcgfkceghdgngdglj.0

Crucial Memory Search for Toshiba Laptop:
http://www.crucial.com/store/listparts.asp?Mfr%2BProductline=Toshiba%2BSatellite&mfr=Toshiba&cat=RAM&model=Satellite+335CDT&submit=Go

Additionally, you can search eBay for the memory, and find many
offerings, although the quality, reputation, return policy, etc are
all very different.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3423781443&category=31574
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3423781883&category=31574
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3423498219&category=11172

etc.

I hope this helps you in your quest to upgrade your laptop!  If you
need further information, please ask for clarification.

Search Strategy:

Toshiba on Google:
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=toshiba&btnG=Google+Search

Used 128 on Pricewatch
http://castle.pricewatch.com/search/searchmc.idq?cr=Used%20128&qc=%22USED%22*%20AND%20%22128%22*%20AND%20%40totalcost%3E0%20AND%20%40minorder=1+AND+%40ctd+281&i=281&ct=NEN&c=NEN-Notebook%20Memory&mi=N&m=N&ne=13620&l=13574

Crucial Memory Search for Toshiba Laptop:
http://www.crucial.com/store/listparts.asp?Mfr%2BProductline=Toshiba%2BSatellite&mfr=Toshiba&cat=RAM&model=Satellite+335CDT&submit=Go

http://www.pricewatch.com/1/33/1078-1.htm

You can always try pricewatch(url above). It's EDO RAM, your max
capacity appears to be 160MB, and I think that model only has one
slot... From what I have seen, no one manufactures what you need
anymore, you may have to settle for used, but most good places do have
a return policy.

http://www.crucial.com is an oustanding manufacturer with a rock solid
reputation and lifetime warranty.  They sell some forms of EDO ram. 
However, I strongly advise you to call them first to see if they have
any input, as the satellite you mentioned is not in their memory
chooser and thus there may be some issues they know of that make it
inadvisable to purchase certain types of memory upgrades for your
toshiba.