air pump accessories store price
Airline tubing   (by the foot)

Buy only as much as you really need. May save you money. You just have to ask your fishstore for it cause they usually keep it behind their counter (hence hidden from the innocents and the clueless LOL)

20 cents
Airline control 11 piece kit 

Includes 4-T valves, 5 air control valves, 2 suction cups, so you are covered. You can do all kinds of crazy air control maneuvers with this great weapon!! :) Don't go to battlefield without it LOL.

$3.00
PennPlax  gang valves- 2 way valve (up to 5 way valve)

Allows you to regulate airflow, a must with bettas especially when setting up a breeding tank. This one has a feature that allows it to easily hang from tank's edge. Easy to adjust air control knobs. Lasts. Good quality/price ratio :). My valve of choice. 

Pictured left: a 3-way Pennplax gang valve.

$5.00 
to 
$8.00
Air stones (2 units)

I really shouldn't have to explain this one, but just in case you are retarded (LOL) this is the little thingie that makes little bubbles in the water (woaw!!!) (cool dude!). Since one has to replace them often, I suggest the basic, simple and inexpensive ones. The fancy ones cost 6 times more and poop out on you just as fast ;). (or faster??) >:((
$1.75