You do actually need to read what I've written.
Specifically, if it's complicated and time consuming we would write into the contract a requirement for staged payments.
To be fair we regularly give out credit accounts in excess of £10,000; I don't really consider 2000-5000 to be a lot of money. Most years we would write that much off as bad debts, but given the very small percentage that it is of our turnover, it really doesn't concern me too much. I expect to get a bloody nose from time to time, and it doesn't surprise me when it happens. Provided I can keep it to an acceptable level that's all I'm bothered about.
We have also taken director's guarantees in the past and persued the director personally when payment has hasn't been forthcoming. IF we are unhappy with a credit report, and a guarantee isn't forthcoming, then, and only then, would we discuss prepayment.
Running a business is a risk at the end of the day; but these days so is working for someone else. At least I control my own destiny.
I should add I've been around the block a few times, and have seen companies that I worked for hit for bad debts in excess of 6 figures which ultimately meant the demise of three of them. They weren't my accounts, and that is in effect where I learnt the lessons of giving credit (ie with other people's money). The most obvious thing I learnt was never to be a busy fool (low margins do not a happy camper make when it goes belly up).
To answer your question though, £2000 wouldn't be en ough to trigger alarm bells really, somewhere around £3000-£4000 might with a new customer; it all depends on their history really.