Subaru bouncing/high revs on idle

[Lingy]

Hi all,

I had a rev bouncing issue on my Subie a month ago and had it checked out. 

I was told that it was the idle air control valve that was faulty and that also the rubber gasket was broken.

The garage I went to went and looked for an aftermarket part just so it's at least usable for now, but suggested to get a 2nd hand OEM one.

At the moment with the aftermarket one, on cold starts, the revs are super low, like 100-200 rpm on the verge of stalling. It also gets quite low on early parts of a journey.

I'm trying to source a 2nd hand OEM one first as new ones are like £400 from what I can see. 

Is there anything I can do to be careful with the car while I'm trying to find a 2nd hand OEM IACV? Generally I don't push the car hard even before this was an issue.

Or if anyone knows where best to look for 2nd hand parts, outside of this forum?