Two examples of why it's better to source parts yourself and not rely on other or hearsay.
 I use to buy loads of gas struts at one time and believe it or not RS were the cheapest at £42 for a pair, On day a set came in with their sticker across the original suppliers name. Gas Springs at Coventry. So trying to save a bob or two i rang them up to see if they would supply, yes no problem but they wanted a minimum order of 10, no problem as we used plenty. Came back with a price of £38 plus delivery, remember RS is free but decided to get one batch to see if we could do better once we ordered. "OK 10 pairs of springs at £38 per pair, I'll order "
"No Sir that's £38 each !!"
When I pointed out that RS were selling them from them for £42 a pair he told me they didn't sell that cheap to anyone, I told him to look at their then site them and put the phone down.
I also buy reasonable quantities of Tufnol sheet in thickness's from 3mm to 25mm, again I used to use RS who could manage to beat all the suppliers who rang up. I then found Direct Plastics at Leeds who have all their prices on line.
I was then told by someone that they were expensive and to use a plastics company at Coventry I think it was who supplied Direct Plastics. Another phone call and finished up with prices 1/3 above DP's pricing. When I queried if they did supply DP yes I was told they did and they were cheaper. I had to ring for their prices, DP's are on the web .
Often when you factor in carriage one stop shopping often makes sense, also it a different ball game if you are only buying or need small or reasonable quantities. What I pay for one bar of material is nothing like Mark pays for 42 tonnes.