I'm new to doing any type of landscaping and have never roto tilled before but my partner has a lot more experience in landscaping. We have a regular customer that we mow each week (front yard only) and the backyard is mostly weeds and debris and a little bit of grass that hasn't been mowed in months. One day while mowing the lady asked us to give her an estimate on how much it would cost to roto till the back yard so she could plant grass seed. Being new to the tilling scene we had no clue what to charge but estimated it would take close to 2 full days of work between the both of us. So we quoted her $1000 and she said, "that's not bad at all, when can you start". We told her in 2 weeks. Well, today was the day, I borrowed a commercial rear tine self propelled tiller from my inlaws (we included the rental of the equipment). We started removing debris, mowed everything down to nearly nothing, and poked around for tree stumps (found 1 that was very brittle), roots, etc. We encounterd about 20 to 30 Yellow Jackets so I had to run up to Home Depot and get some cans of hornet spray in hope of finding the hive but we never did. So the entire time we were watching each other's backs so that hindered our progress quite a bit. Another unexpected thing was that we found around 27 different sized round stepping stones about 4 inches deep while tilling and also found a full layer of black plastic around 2 inches deep. Also there were small round landscaping rocks all over the place and the tiller didn't like those that much either. LOL Suprisingly enough we got done in about 7 hours even though we stopped to fight off Yellow Jackets and had to pick up all of those stepping stones (the customer said that her husband put them out there 17 years ago and she forgot all about them). We walked out of there paid in full. I was wondering what you guys would do if you over estimated the time but when you did the job you got done early but also encounted a lot of things you could never know about until you started? I'll try to attach a pic...this pick shows just one section of the back yard, not that big but there are 3 sections about the same size if not a little bigger.