Scuddlebutt3 is a good point to find microscope supplies on ebay, they deliver fast and combine postage. They stock all the standard slides, cover slips, stains, and sample pots.
This member carries good stock of scientific glassware etc. She packs stuff very well and delivers fast.
Also very good communications- I had trouble with my paypal account after one purchace and this member was very patient.
As the name suggests, a good place to look for glass tubing (small diameter) and silicone items.
Eg6554 also a good source of lab glassware, bottles, and other items.
Leeraph has stocked some petri dishes in the past, and I would recommend him as a good member.
Firstsupplies are a top source for medical stuff and first aid kits, also training dummies.
Tubcats sent me a nice little hygrometer meant for hatcheries but very cheap and useable.
Tat2daveb supplied me a pack of canulars, and keeps a good stock of different sizes along with other gear for tatoos/piercing that can equally be used for scientific purposes- the canulars are all sterile.
Scocky stocks agar and other microbal items including peptone, nutrients, petri dishes, and a vast array of canulars, needles, syringes and scalpels.
sixbells24 has a good selection of glassware for the lab and is a good guy to deal with.
Ba.supplies carries magnesium ribbon, crystaline iodine, and some other chemicals that find uses in the lab.
All the above, I have dealt with and found to be exemplary in service and products for science gear and I can recommend them as honest and knowlegable. More power to them!
Please write guides like this- it keeps a tight community and pushes out the bad dealers.