Stuck(?) - needing new ways to purchase fix/flips

Fixing & selling homes is no sweat (well, unless it's a hot day) in the Denver Metro market. However, finding & funding them is the tricky part. Just finished Flip #4 - sold without putting on market to a party interested in the project. Here, even a lousy property with severe issues sells for more than we want to pay. We found 3 of the Flips just mentioned pre-market by word-of-mouth & still paid a little too much, but the last purchase/sale made up for that. Looking for flip #5, right now and so on. Still trying to pay down debt & get some cash for leverage & quick sales, which seems like it is taking way too long. Would like to buy wholesale, pre-market, auction, etc. but need the almighty cash. So far have used expensive HM loans - 9-12%. The lending firm I'm using promises me a better rate of 8.5% on the next, but it still robs us of a chunk of cash until the project is over. Ideally I'd like to find a LINE of credit of some sort. My credit is excellent, but of course being self-employed must go off my REI history rather than tax returns to borrow. Have 2 holds, and a history of several other successful flips/holds in CA. Any and all suggestions from experienced investors are welcome!