Osolow,
The round 4" porch light can be had at Vintage trailer supply too here...
Vintage Trailer Supply - Vintage travel trailer parts and supplies!
As for the step light, you may need to get that from an AS dealer. Have you considered re-plating the exisiting fixtures???
You may also want to look at a local auto / truck supply shop for your lighting needs. They are all pretty much standard light fixtures. I was able to get marker / clearance and the 4" porch light locally which saved me a few bucks in shipping and the actual cost of the lights.
As for quality, I think they are all bout the same, not very good

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