do you know if any of these allow to buy them in bulk or best for me to ask them myself? bulk at cheap price?
Most of the suppliers listed above are wholesalers, so yes, the more you buy, the cheaper the unit price. And yes, it would be good to contact each of them directly to negotiate on price. If you haven't yet, do send them an email asking what the best possible price is that they can give you for the products you wish to buy.
Let us know how you get on. All the best!