Next step when extundelete and testdisk fail?

I accidentally deleted a large compressed file on an ext4 file system. Unfortunately, I didn't realize that I'd done until a couple of reboots. I tried extundelete, which just told me it couldn't recover the file and testdisk decided that the file was 0-length, so it restored a 0-length file. I called a recovery guy who told me I'd have to commit to several bills before he was willing to try. Since I'm not very confident that it could be done, I'm not willing to risk that.
Is there anything I can do? Is there some way I can at least confirm whether or not it's lost forever?
My system is Ubuntu 16.04.