In my experience, a lot of these companies don't even have a store front, so if you do not have an account manager, they will have to set you with one first. At my company we would normally have to fill out an internal work order, so our purchasing department would ask the resellers they have contact with for a quote. Then the phones start to ring!
For my hobby gear I have dealt with companies such as Electro-Meters.com (Rigol Distributor in Canada), and even though they do not have a store front, the purchasing of equipment was pretty straight forward, same goes for RAE Industrial Electronics, where you can almost feel they are so used to the "give me your PO and I will give send you a quote", that my guess is that is a bit awkward for them to deal with the hobbyist lot, although I must say they too were really nice to provide pricing for several devices in record time, with no Spam e-mails or follow up calls that I can recall. Not the most straight forward transaction, but I would certainly go back to these two companies for more down the road and even recommend them to the "general public".
Now if you are talking about companies such as most listed on Labx.com for example, then yes, I think they have such tight controls on distribution and pricing, to keep the discounts at a minimum, and so they can add other services of their own to the quotes they will send you, as "value added" options you will surely need!