I ordered my YH from Amazon due mainly to their excellent return policy (it has the right labels on the machine). I have always been able to return purchases by clicking a few boxes to explain why and taking the purchase to their designated drop location (local). I did not buy the extra warranty, I've seen poor reviews from others that tried to use those. They are nearly always a waste of money (cars, appliances, etc.). I think really good oil is not a waste of money. I use Nuvair. I order things from Alliexpress (like extra white elements for the stock YH filter) but normally only relatively low priced items I don't think I'll need to return or need warranty service on. Sometimes their shipping is included or reasonable but often recently it has been prohibitive. I agree an extra filter is appropriate, especially if you are filling SCBA tanks but I don't think the big gold one is necessary. I have one but do not use it. I had a smaller black one first and I filled it with color change dessicant. I change the white element in the stock filter after every tank fill but rarely have to change the color change beads. Seems like they are not seeing hardly any moisture. I have both filters above the YH so water drains back to the compressor. I vent every 5 minutes and noticable water comes out. I put a one way valve in the outlet of my extra filter. That way I do not have to worry about the SCBA tank pressurizing the YH or air escaping the SCBA when I vent the YH and turn it off. But if you do that, do not dead head the line out of the filter. You have no way to vent it.
Short version, I recommend Amazon purchase so you can return it easily if there is an issue, Nuvair oil, extra filter with color change dessicant but not necessary the huge gold one, and a one way valve in the output of the extra filter.
