Your price range should be more than sufficient for a first class system with top grade components from the major online outlets such as Dell, Mesh, Evesham etc or built to your specs by a small, perhaps local, firm.
Notwithstanding the fact that it will either be 1) cheaper in a few weeks' time or 2) have an even better specification for the same price, you should not take too much notice of individuals' complaints about this or that company.
The major suppliers each build thousands of systems annually and, by sheer weight of numbers, there are bound to be some customer complaints.
These may not be the system builders' fault - supplied components may be faulty or go faulty shortly after first use, or the customers themselves may actually cause the problem because they don't know what they are doing.
I would do some research, work out the specification and software you require for your needs and then look for a supplier or system builder who will deliver it equipped with top grade components, hardware etc. Get the specification fully detailed in writing.
Just ensure that the warranty is of an equally high standard, pay for it by credit card and you shouldn't go far wrong...:-)