Hed sells one directly. I got it for about $40 without the axle.

JB Welding it seems like a good way to ruin your wheel. I tried it on my wheel and it kept spinning off and eventually ruined it. You don't really need a lockring on the track unless you're doing match sprints, and the guys you race against like to slow down A LOT (which is unlikely).

Use the rotafixa method and just get the thing on there tight, you'll be fine with just the adapter.