What size and brand of cheap tires for 97 RT100?

Stock size is listed as:
FRONT TIRE 2.50-18
REAR TIRE 3.00-16

So what tires can I put on this that are good and cheap. Wanted to try the Maxxis IT, but they don't list them that way.

Can anyone recomend a good CHEAP (bike is not worth spending $60 per tire) off-road tire and size?

Thanks,
Phil

Will a Maxxis IT 90/100-16 fit in the back ok?

Phil