It's quite common practice outside the outdoors industry - where prices are volatile, like with RAM, or - I've always assumed - retailers are prepared to bob and weave, for ads and web sites to follow this practice.
As far as the outdoor brands 'price fixing', erm, dunno. It's a fairly hefty allegation. Don't manufacturers retain the right to supply whoever they want to? Or not. As the case maybe. Remember all the fuss over Levis and Tesco?
Some manufacturers are wary of web retailers, because ecommerce in a lot of areas, has become synonomous with discounting and they don't want to be seen to supply retailers who are undercutting their bricks and mortar retailers - still their main source of sales.
On OM we're all in favour of giving people the choice, which is why you'll find online retailers on the shopping pages, but you can also track down your local shop using the 'My Local' link at the top left of this page, if you're a member.
At some point you reach the debate that cyclists have over web retailers versus local bike shops. Viz, you may be able to buy cheaper on the web, but you have to weigh that up against local expert advice, friendliness, instant purchase etc. Of course, if your local shop is cack, then that doesn't really matter.
Presumably the manufacturers can legitimately choose not to supply anyone they want to. James, as a retailer, is that the case? It would seem mad otherwise as you'd have no control over the quality of outlet supplying your product.