But a complete tank rebuild kit. Sounds like the bolts holding the tank to the bowl are leaking. So as long as you're taking it apart anyways, may as well do a full rebuild. The cost for materials, per toilet, should be less than $50-bucks. If you have a good place to work, take the tank outside and once you break it down, hit that tank with the hose (or pressure washer). Get it good and clean. While you're outside and have good light, carefully inspect the tank for cracks. if you have no cracks, do your rebuild while you're outside. If you have cracks/hairlines, take it to your plumbing supply company and have them match up a new tank (about $125). Throw the old tank in the trash. Carry the rebuilt/or new tank inside and bolt it back onto the bowl. This is your cheap fix. When you bolt it down, tighten right side, then left side, then right side. Just keep good even pressure, same as you would change a tire. Don't want you to accidentally crack the bowl. No gorilla grip Mark.
If you hire a plumbing to do the rebuild, you'll likely pay about $400 per toilet. keep that in mind. You can buy a BRAND NEW TOILET for less than $400. Installed it will likely cost $900-1000. I personally like American Standard Cadet Pro. I think the guys around here seem to favor the Toto Drake