If you're looking to raise $125,000 on your own then you're spot on HELOCs and refinancing existing properties might be 2 of the best ways to do so.
A couple other options could be transferring your 401k or investment accounts into a self-directed IRA account and leveraging that money for all or a portion of the required capital. You could also look to get a cash advance on credit cards, but as this is a highly risky option, I do not advocate using this one.
Lastly, I would encourage seeking a potential partner to do a joint venture on this deal. If they bring all the capital to the table this could make your job a whole lot easier and lowers your risk. You could give them a fair cut of the deal and it's a win-win. A small piece of a big deal is better than no pieces of any deal.
JV or working with one other investor could be a way to go. If you can work out a deal for them to hold a second on the property that you pay interest, for example, then that would avoid the syndication process.
Other options would be lines of credit, refinancing existing properties, leveraging other assets (using a paid off vehicle as collateral, for example), or selling other non performing assets.