here's a few ideas to keep the cost down

1. instead of buying filter sponges use the cheap foam sponges that you get out of hardware store for cheap paint rollers 
2. instead of aquarium lights tubes use normal light tubes warm white ones are best
3. do you know anyone that keeps an aviary out doors dig the ground up free white worm and earthworms 
4. want a reflector use tin foil  stuck in a gutter pipe
5. need a quick filter use a small tub and a small pop bottle (non glass) put some holes in the bottom of the pop bottle and stick it to the tub add some gravel to the tub and an airline  hey presto a small corner filter
6. too many air pumps then make an air reservoir look on one of the big aquarium sites for details 
7. guppies dropped fry in your only tank use some ice cream tubs or Tupperware tubs as an emergency fry tank
8. find a good fish shop not the cheapest one
9. join your local fish club
10. join your local fish club now