So, as I do in such situations, I figured I ought to make one myself. I haven't entirely succeeded, but for approximately $60 in parts, a partial solution is great.
(Bad phone pictures inbound!)
That's my 72" yarn swift from Fiber Artist Supply Co. clamped to a base made from bolts, nuts, and a chopped up 2x4. The swift comes with the wooden pegs, and is quite nicely made.
And that's the mini-raddle. The wooden base and clampy bit is improvised from wood and thin plywood, and the raddle itself is a steel pet comb cut in half. (The spine on the linked comb is aluminum so it comes apart very nicely with a hacksaw.)
I haven't used this very much yet; it has an absolute lack of tension control, so I can't wind directly on to my loom without the whole thing flopping all over and dumping all my warp on the floor. It's just fine for winding sections that I'll chain off and beam later, though! I still find it a lot faster than a warping board or reel.
I will probably build a new wheel head to replace the swift at a later date, so that I can add tension control and a place to clamp the mini-raddle.