After calling and personally going and talking to many tree services~and I mean, I stopped along the highway and talked to crews working counties away, inquiring as to where they were dumping their chips that day~at their offices and out on their work sites, I was drawing a huge zero. I did find some really poor quality chips dumped a couple of counties away~just by driving by the site and begging the landowner for some~ and was able to get some of those but they will take forever to compost~huge, stringy, mostly evergreen stuff.
I even made a huge sign and placed it out by our mailboxes, directing any tree services to dump chips on our land.
Finally, someone suggested advertising for chips and, as implausible as it sounds, a lady called me and told me of chips that had been dumped illegally on her land by the neighboring state park and said I could have any I wanted. I got some of those, then my neighbor had an electric right of way cleared and those chips came my way. With all of that, I finally got 4 in. on the garden, so added more depth with 250 bags of leaves gathered in town this fall.
I went back to the place where the lady said I could have chips and the state park had removed the chips and leveled off the piles...I was still able to scrape and scoop a little more from the site, but my supply of chips is no more.
For what it's worth, you might advertise for chips....you never know what will happen. Tell everyone you know you want chips, you just might get a lead on some. My sign at the road almost netted me the motherload of chips....a fellow in a semi tractor truck stopped and wanted to dump his whole load of chips but couldn't get his big truck back our switchback driveway.
I hope you find enough to get you started. Remember, they need to mulch down for several months before you will be able to get the best results out of them...at first, the wood chips rob nitrogen from the soil where they come in contact with the soil, so there are nutrients locked up until those start to mulch.