Amazon is often higher priced, but with shipping and time, Amazon seems to beat RockAuto on many items. An example is I need a Bonneville rear shock mount. RockAuto lists for $16.16, Amazon $21.25.

RockAuto total is $22.59 (with discount applied and shipping) and arrives August 5.

Amazon total is $21.25, that includes free two days shipping (I am prime member and arrives July 31.

I know Roy often gets next day arrival of parts he orders from Rock, I have never had parts arrive in under three days. Roy must get the Rock VIP treatment.

This is a valid point, especially with single parts. It definitely pays to weigh your options when it comes to parts these days. Ebay is also worth a look too.

Another factor to consider is part warranties, and how they are executed. How does Amazon fair with this?

I always check Ebay, Rock Auto and Amazon for comparative prices. Typical delivery time for Rock Auto is 2 days, never more than 3. A couple of weeks ago I ordered a turn signal switch for a friends car off Ebay at 4PM on Saturday, and it was delivered Monday morning. Other times it has taken over a week. If I absolutely must have a part by the weekend I order from Rock Auto by Tuesday. If time is not a factor, I order from the least expensive source.

RJ, that is a very good point that with qty- RockAuto can become much more competitive. The key is often that all the parts from RockAuto need to ship from same warehouse.