This is not a premium mower. I'd much rather have a new Lawn-Boy Insight with Tecumseh for that kind of money. $150 is plenty for a used HRR.

It is worth whatever you can get for it. That is often a lot less than what you paid, and what you would hope for. Antiques Roadshow has convinced many people that old=valuable, and in some cases it is. But usually not. Check your local Craig's list for a couple of weeks, and contact the sellers to see how they made out.

Your current salary in an unrelated field should have no bearing on what you would charge, IMO. The only relevance it has is in helping you decide whether quitting your day job for the project manager job makes sense for you financially. IOW, you can decide that switching careers will work for you only if you can make X% of your current salary. There are websites such as salary.com that show pay ranges for construction project management, which you can then adjust for you own levels of education and experience, the requirements of the new job, and the fact that you'll be paid as a consultant and not an employee. Also, if you know others in the real estate rehab business, you might be able to get info from them. If you think about it, it's not that different from evaluating bids and estimates from subcontractors. You want to get a feel for the local going rate for that type of work. It sounds very exciting - I hope it works out well for you!

Is the labor warranty from the dealer or a manufacturer. Third party labor or extended warranties are problematic. If it's a dealer only warranty, it's only as good as the dealer is willing to stand behind it. Get the warranty in writing and specifically understand all exclusions. That's the best advice I can offer. The big ticket items as far as replacement goes of course would be the compressor in the outdoor condenser and var speed blower motor inside air handler. Most of the electronics can be pricey to replace but the labor generally is not a big factor. Leaking coils can be an issue. And not meaning to scare you but Lennox is behind the curve in this area as far as best material. The difference between the labor warranty may be more of a selling tool. I personally would lean toward the dealer you have the most confidence in as far as a good install. IMO