My advice is to look on ebay, regularly. I've just picked-up a top-condition Bowens 3k ringflash for as little as £300.00. I missed one, a few weeks ago, which went for £150.00, though that was a much earlier model. There's not much to go wrong with them, and they are easily serviced by a professional workshop. Of course, this assumes that you have a power pack to fire the unit. If you don't, you can pick up 1.5k and 3k Bowens packs on ebay, too. I've had several, recently, as spares. Bear in mind that the older Quadmatic packs aren't servicable, now, due to lack of parts, but the newer 3k packs are still viable. The Bowens ringflash has two 1.5k tubes on two cables - so the very old, single-outlet packs will need a double-head adaptor to work the ringflash. These adaptors seem to fetch funny-money on ebay, though. Way too-expensive.
To be honest, you don't want too-much obvious ringflash work in your portfolio, so you might find that renting some kit, here and there, will suit you better, as you build your book and your career. Ringflash is in and out of fashion like a revolving door, but if you take the time to find ways of making it work, outside of the obvious, frontal effects, than you can justify keeping a unit in your kit.
I looked at your online portfolio. It's really coming along very well. Good luck.
Shiner