I am looking for a place that sells restocking supplies of Weapon Repair Kits. The only place I know of is the DLC vending Machines in Dead Money. But outside of DLC where can they be bought with caps. Also, another item I need to find a store that sells in antiveonom? Can anybody give any ideas what stores well either or both of those items I have had no luck finding any sellers.
-Thanks in advanced for any helpful answers!!

I don't think anybody sells them. However, the Gun Runners do sell the components required to make them.

You need Repair at 50 to make Weapon Repair Kits, which I would recommend you do. You can make antivenom with Nightstalker blood and Radscorpion Venom (the green scorpions, not the brown ones). I don't recall how high a Survival level you need for that, though. Sometimes it's just best to spend the points so you can make your own. Though for the time being, a lot of Legionnaires carry antivenom.

Pickup EVERY piece of Scrap Metal, Electronics, Duct Tape (which of all the items in the WRK is the most elusive) Wonderglue and Wrench you can find. I'm on my second playthrough and went in knowing that I was going to do just that. I've made at least 75 WRK's and used many to fix guns I've later sold off for HUGE profits.

Anti-venom, kill every Radscorpion and Night Stalker you can find. Goodsprings is literally surrounded by scorpions, over in the mountains behind it (be careful of the Cazadores though) and over in the valley passed the cemetary. Legion soldiers also carry anti-venom from time to time. I believe you need a Survival of 50 to make Anti--venom.