i dont know how big your tank/tanks are but i just got the Top Fin brand mini gravel vacuum at petsmart for $2.49 (i have 3 small under 5 gallons betta tanks so mini size is good for "us") but even the largest vacuum is less than $10 i think. and they have this "self starting" thing where you just pump it up and down and the vacuum part fills with water and the siphon begins, i didnt think it would really work but it does, even in my tiny 1 gallon tank! the only other DIY siphon/vacuum ive made was for my tanks at first, i took a large straw and stuck the airline tubing in the straw and taped it up at the "bendy joint" in the straw, a "tiny tank vacuum" other than that i would say to just buy one.