First of all, I am a big fan and user of Manager, and am very impressed and happy with this program.
I have a beauty salon, and by hair products etc to use for my services.
What is the best way to process the inventory that I buy, as I do not resell the product (except every once in a while) and I do not have invoices to send to the customers
Don’t use the inventory module. This is mean for products that you buy and then sell, not for consumables that you use to carry out your business.
I would use Purchase Invoice Items to buy the goods and you can use Sales Invoice Items for the odd hair product sale.
However, if you don’t provide invoices to customers then you don’t really need Sales Invoice Items either. Just receive money in bank account and select sales as the income account.
Inventory Module is not relevant to your business. However if you want to physically keep track of consumables bought, I believe that the warehousing module coming out soon will help with that.
Okay, thanks a lot 
Technically speaking, you can utilize inventory. This way you can track how much you should have on hand.
Since most of your products will be used by the business rather than sold, you need to use Inventory write-offs tab to record each inventory item you use. Inventory write-offs will basically allow you to decrease your inventory count and allocate the cost value to some expense account.
Purchase Invoice Items / Sales Invoice Items no longer exist and have been replaced by Non Inventory Items.
Please STOP asking the same question under different topics.
I also work in beauty salon. We use manager too (without inventory mdule) and are very satisfied with it.
It might be an idea to ask Lubos to lock threads older than six months as far too many people are responding to three year old threads, particularly with out of date information.
The problem is that there are more than 13,600 topics. The practice is to leave them open in case they are of interest or use to someone. When a topic clearly addresses a user-specific issue (such as a personal equipment error), it is sometimes closed. Or when questions arise that indicate a high potential for misleading users, a topic might be shut down. But most, as in this case, are valid comments about the program. So, in the interest of stimulating discussion, they remain open. It’s really up to the moderators.
I am not expecting anyone to manually close 13 000 topics obviously. The forum software should be able to automatically lock posts that have not received responses for more than a certain time period.
Closing the post does not hide the post, so the information is always and still available to anyone who wants to read the post. If somebody really wants to respond to a topic that is old they could always link to that topic.
I just see too many posts where people are responding to a post that has long since been closed because they don’t realise how old the topic is and too much of the information is out of date. You may not realise how misleading the information is because you are very familiar with the software but a lot of users get easily confused.
good to see more information about salon