RS as in the UK electronics distributor known as Allied Electronics in the US or Radio Shack?
DigiKey is fine, they are a top notch company and I have never had an issue with them... My primary supplier is Mouser, but I often place orders with DigiKey when Mouser is out of stock or for components that Mouser does not carry... I also use Allied Electronics (RS in the UK) as well, they have some great prices on certain components vs DigiKey and Mouser... Sometimes there is a big enough price difference to justify a separate order, same with other companies that I place orders with... Never assume you are getting a good deal all the time just because the company has comparable prices on most components, sometimes you will be totally surprised at the difference on certain components from company to company...
BTW I generally use Mouser and DigiKey as most of my orders are shipped overnight, and they provide same day shipping on most orders, even when placed in the late afternoon or early evening... This allows me to get an order together early in the day and add to it as the day goes on before finalizing the purchase, as it never fails that I forget to add something the first time around...
On the other hand if you are comparing DigiKey to Radio Shack it's absolutely no comparison as Radio Shack is a total joke nowadays and only good for instant satisfaction if they happen to have your part in stock... They used to be a good source for 1lb rolls of solder as I could avoid the shipping cost and they were actually comparable in price, but at least by me they no longer carry the 1lb rolls so that plus is gone as the smaller rolls are marked up substantially...