Ask The Experts About 3-d Dna Model Ideas

DNA molecule model,HELP!?!?

i need make a dna molecule model. 3-d i guess.
like with form balls and stuff. i went to the store micheals and it cost alottt for everything about $50; 4.99 for 12 balls,i dont want to spend that much.

does anyone know where to get cheaper form balls?
or ideas for other things to use?

possible some details on HOW to make a dna molecule.im clueless on this :[

please and thank yous!
:]:[ haha