I have the opportunity to purchase a used Bluebird 424 plug aerator for $400. I have never rented/used a walk behind aerator (or ANY aerator for that matter) and am a solo operator that has been considering offering aeration as a service to my customers. I've read numerous comparisons of brands and models on here, but most that speak of Bluebird are of the 530 model. Would the 424 model at this price be a suitable starting point to begin aeration? Most of my yards are relatively flat...a couple with slight hills on them. I haven't seen the machine in person yet, but it looks to be in good shape from the pictures. The seller said he had it tuned up recently and that it has a briggs engine on it, he thinks a 3.5hp. (He was not at home when I called to inquire). Bluebird's website says it has a 17.5" aeration width. Any pros/cons about this particular model would be appreciated. I also haven't been able to find the m.s.r.p. on the 424 unit. Anyone know what these go for new??