You may also be able to avoid buying a SS kit if you have a few items kicking around.

Cogs and spacers can be sourced from old cassettes. Unscrew or cut the bolts holding the cogs together (on many, not all cassettes) and pull apart the cogs and spacers. You'll likely need more than one cassette's spacers, or you can cut down tubing of the appropriate diameter to fit. I recently used some copper, and I've seen folks use PVC. You'll need to either measure the chainline or be willing to futz around with the cog position to get it right. Keep the old lockring from the hacked-up cassette to hold it all together.

Personally, I love conversions. I ride on the road, I like SS. No brainer for me. I'm not too interested in riding a track bike on the road. Horses for courses and all that.

My recent freehub setup so you can see what I'm getting at. From the inside out, I have a plastic cassette spacer (keeps the copper from bottoming out on the hub shell), then copper pipe cut to length, re-used cog, plastic cassette spacer, really think metal cassette spacer (to give the lockring something to bite into, in the past I've also used the smallest cog here as it has the indents that register with the lockring) and then the lockring. I had to be sure that I set things up so that the lockring tightened up against the whole assembly before it bottoms out on the freehub body.