Hi Jon
When you wrote your post I didn't realise you were buying for your villa development. When I bought a pile of plants for our house, I did it the 'mysterious' way, they didn't know that the plants were destined for a bule house. The first nursery I went to, I went and the price was ridiculous. I took pictures of what I liked. Then I showed the pictures to my husband (a local) and he went and got the same plants for a fraction of the price.
For a business, if you don't have a business manager that can sort this out for you, my advice is to tell them you are buying for your development and if they want the business, and continued business in the future, then you need local price. Otherwise, tell them, you can buy from Bali but you'd rather not do that as it's better to give some business to Lombok because so many other things have to come from Bali. See if they can shift on price - otherwise maybe carry out your threat. Competition is much more in Bali.
Freo