A trilane for your carry
This may or may not be an issue, depending how many heroes the opposition puts against your safe lane, and how good they are at looking after themselves. If you're running a hard carry like
Spectre, especially against another dual lane, don't expect them to be getting epic farm though.Mid 
Tangos
One support is unlikely to be able to get more than 1 set for regen, and will likely have to do without a
Healing Salve. If they've got a relatively easy lane, they might be able to afford to give you 1 Tango. You might have to buy some yourself.Detection and TPs to mid / offlane
A biggee. Each hero gets 625 starting gold, and 100 per minute income without last hits, assists or jungle creeps. That means our sole support likely has about 1700 gold in the first ten minutes without assists, and just a few jungle creeps from pulls.
They probably need to buy:
Animal Courier = 120
Flying Courier = 2202 sets of
Observer Wards = 3001 set of
Tango = 1252
Claritys = 1002
Iron Branches = 100
Boots of Speed = 450= 1415 gold. This leaves them just 295 gold to play with, assuming they don't die, need to buy more consumables etc. This isn't even enough for 1
Town Portal Scroll, and 1 set of 
Sentry Wards.Invisible heroes especially enjoy ganking AFK junglers. Do the maths. Maybe you need to help them out?
Ganks to mid
1 support hero may struggle to provide enough to help you get that vital kill on mid, even with a rune. Even assuming they can give up their stacking/pulling/denying/supporting duties in lane without screwing your carry over.
A timely 
Mekansm or set of 
Arcane Boots
You know that guy who's buying all the utility consumables your team needs? Yeah, they don't have much gold to put towards vital early game teamfight items. Maybe you need to buy it yourself?
Summary
Consider hard before leaving your team in this situation - maybe the enemy lanes are weak and the game passive enough for you to get away with it. A team can get by with 1 support and still win, but you have to weigh up the likelihood of that.
One thing is absolutely for damned certain - don't moan at your sole support if you don't have everything you want provided for you that you might want. Maybe it's not the end of the world if you have to occasionally buy a set of
Observer Wards or 
Dust of Appearance?Perhaps you could click on their hero and see how much gold they have before kicking off about the lack of dewarding going on? Maybe they genuinely can't afford to buy you a
Town Portal Scroll because you just died stupidly in lane?
I guess what I hope people take away is that if you are sick of that drow always just running away with her shadowblade then buy some dust... no matter who you are or what item you need. Greedy teams and 1 support teams can certainly work, you just need to actually communicate and think about what items are best for the current situation.