Terry Love has a great website with toilet reviews, and it's where I learned to seriously respect Toto toilets. His site is invaluable for research.
This next bit assumes you have a standard 12 inch rough-in for the toilets. If you don't, all bets are off, and the recommendations are worthless.This said, we needed to replace a toilet a few months ago on a budget (which excluded buying a $400+ toilet), and I did some digging around and some research. There are some plumbers who complain about the things, but apparently the Lowe's house brand
Aquasource AT1203-00 is a
Consumer Reports Best Buy toilet at only $99, and has a lot of positive reviews - though it is an ADA compliant "comfort height" bowl. We couldn't fit that model in our bathroom due to the length, but the cheaper non-ADA compliant
Project Source T803 did at $88. Before buying it, I looked at the bowl, drain and tank design, and everything was identical to the AT1203 with the T803 design wise... and despite the sales person insisting the Project Source was "contractor garbage" all the while only talking up $300+ toilets, I took the chance. We love it, we can't kill it or clog it, we don't have "dirty bowl" problems, and it works great. We were convinced for a while we'd need to spend $400+ on a Toto for this sort of HET toilet that didn't clog, but the $88 model surprised us. The downside at the price is the quality of the fasteners (not solid brass, just brass plated), but you can upgrade to solid brass for everything for well under $10. The seat included is also cheap and shoddy, but easily replaced/upgraded as well for another $10-15. Of course, YMMV, and you can't return an installed toilet for a refund, but it's worth a look and some research.
If you're looking at price solely though and had the thought that if the cheap Lowe's toilets are that nice maybe the HD ones might be as well... not so. The HD toilets at the same price points aren't near as nice and do have a warranted reputation for clogging and other problems.