using mission computer or Resedit
I read in another forum that setting the Spob's tech level to 200 would force it so nothing would show in the outfits. Yet in Mission Computer, the little help window says the number you enter is the maximum tech level allowed. I put in 200 and I got all Available outfits. I set it to 1, and I get very few. I set it to 0, and I get the same few. I haven't tried yet, but do I set it to -1 to get nothing but the special tech levels?
I'm not sure where you read that a tech level of 200 would make nothing available, but as you observed, it actually makes everything available. I'm not entirely sure why you've tried 1 and 0 and have now turned to us to see if -1 would work. You came so close to your solution, but decided to turn to us to find out if it would work. I find the best way to do things is often to just try it out for yourself. 
There are some outfits that, when on your ship, can be sold anywhere...are you sure you don't have these on your ship? I ask because I have a plugin where I made a spob that has a tech level of 0, and a special tech level of 1113, and only the outfits that I created with a tech level of 1113 appear there actually for sale. Other outfits that appear are all there because they're on my ship and able to be sold (but they cannot actually be purchased, only sold).
If I'm not mistaken, you can actually set special tech levels, or even just regular tech levels, to negative numbers, the number lower than the lowest one used being the one that will cause nothing to appear. However, I haven't done any outfits or abnormal spobs for a couple of months so I may be mistaken. -1 does work though, as Belthazar said.
@lnsu, on Feb 12 2008, 11:51 AM, said in How do you make nothing in the Outfits Section on a Spob:
actually, for stock nova, techlevel 998 gives yu everything allowable.
Considering there's nothing in stock Nova with a tech level between 200 and 999, then setting your planet's tech level to 998 would have exactly the same effect as setting it to 200. Ditto for setting it to 420. Or 632. Or 367. Or 835. Or any other number between 200 and 999. So basically your correction was something like "actually, you should call it 'half a dozen' rather than 'six' ". 
On a side note, I seem to recall that setting anything other than the Escape Pod to a tech level of 32767 would make Weird Things happen. It was a long time ago, though, so I'm not certain I'm remembering correctly.
