What areas are you looking to get good service in? Support, Security, uptime, Remote hands, Promptness, bandwidth providers, good specific routes, etc? There are tons of west coast providers that are anywhere from cheap to hundreds a month, really depends on your specific needs.
I've worked with both Quadranet (Los Angeles, CA) and Swift Communications (Seattle, WA). In both situations I was on a tight budget but I feel like I received very good value for my money. Any downtime I had at either location was very minimal and within my tolerance level (5 min a month?).
I choose them because they had good transit blends for my customers. Swift has a $50/month colo option and will probably do that on a mid-tower if you ask them nicely.
Again though, need some more specifics on your needs.
A vegas or phoenix data center would probably be the cheapest in the west.
Power in Vegas costs more than in Phoenix, but either can be a good option. If you want Vegas, I suggest checking out VegasNap. There aren't that many options in Vegas and they seemed to have their act together and good pricing. Although Los Angeles has high costs of living (labor, power, housing, etc), there are some surprisingly good deals to be had there for colocation, so I wouldn't count it out either. Phoenix certainly has the lowest power pricing at the commercial level, so you should be able to find datacenters that are cheaper there than elsewhere, all else kept equal.
In theory Phoenix should be able to provide the lowest pricing. The bottom line is that Phoenix data centers would be considerably more profitable and operate in a sustainable way while when LA/SanJose/Bay area companies compete with the same pricing they do it at break even/loss margins.
It goes to show you how competition affects prices in a increasingly commoditized market because you can still get Phoenix pricing in Los Angeles/SanJose
Well, Phoenix only has to be competitive with your other options in order to be equally attractive. Just because the cost to build and operate a datacenter might be lower, doesn't really change the customer's budget, as most colo customers are not considering building a DC as an alternative to colocation.
Aside from that, DCs in Phoenix certainly have to compete with each other on price to a certain extent, but since Phoenix isn't considered a major market, more of the demand is going to be from local clients whose concerns are a little different than just price. Maybe they care about security, cooling, location, available peers, redundancy, security, etc, which are areas that different Phoenix datacenters can compete with each other on other than price.
For someone who is more interested in colocation and doesn't care where it is their servers are going to be, then Phoenix DCs only have to compete on price to the extent that the price should be equal to or lower than options in other cities. For example, I was able to get a nicer facility at the same price as my previous facility, and then having HE.net on-net at the facility made the total cost for me lower. The actual rack and power costs are about the same for me at both facilities, so, because labor, real estate, and power costs are lower in Phoenix than they are where my previous facility is located, presumably the datacenter is making more money off me. Even so, unless someone is looking to open up another datacenter in Phoenix to take advantage of this fact, it's kind of irrelevant.