"Or is Home Depot/Lowes the best?"

Box stores are never the best choice....sorry.

Local retail nurseries or garden centers will often special order plants in quantity, especially if it is a single plant type. Or the quantity is significant. Otherwise, I'd suggest a broker, like Plants Express.

I looked at Plants Express. That's an interesting option. Thanks.

Please go to a local nursery.

The best answer can depend upon the stock you want to purchase, and your priorities, such as cost, convenience, landscape purpose, etc. If you are looking for specialty plants, such as CA natives, or groundcovers, the best source will be different than if you are looking for 40 common lantana (please don't). If your #1 concern is price, and you want very common stuff, ethics aside, the Big Box stores might have the lowest price.

But if you are unsure of the pluses, and especially the minuses, of certain species of plants, a good nursery that can provide the type of knowledge that can prevent you from planting something you will regret, and be a very expensive and labor intensive mistake.

There are numerous wholesale and retail nurseries on the 126 in and around Fillmore.

There are several on the 118 in between Moorpark and the 126.

Some of the wholesale do have signs public welcome.

Use google maps and call and ask.

It might be worth the time and drive if you aren't close.

Big box retail carry whatever sells even if doesn't do well.

But please don't forget the advice and help we all get from local nurseries is invaluable and they all need the business.