Greatlakes, I recommend this, DON'T go with a rider. You can spend the money and get a good used hydro or even new belt drive for under $3000, which if you are going to GET the $350 a week commercial job, will be an easy pay off. You will gross close to 9500 for the year, based on 27 mows. That is another 4K if you have 5 other $30 yards. Your purchase should be based on how much are you doing? 2-3acres? Or jumping around on islands? The machine you want has to fit your needs. Look at a 48-52" w/b. Get a good trimmer, say $200-250 and a good blower, 100-200. You need a trailer under 1k and insurance (I recommend 1mil/2mil policy Erie has my biz and I only pay 325.00 a year) So for under 5K you can get all you need. You can actually get even cheaper if you get a belt drive and smaller deck. If those are your only mow jobs, you have the time to take longer.
Just my opinion. Look at www.landscapersupply.com
for a nice heavy duty entry level w/b and even ztr riders, they also have a 90 days sac plan. Other dealers like eXmark have special financing right now. I am buying and exmark this year if I grow and it looks like I am. Hope I helped!