I was researching these machines a few weeks ago...
The 'walter 6545' from www.cncdiy.org or their ebay store looked like a good deal and is slightly larger.
For what it's worth I think buying through ebay/paypal gives you more protection than buying direct for a small machine like this if something does go wrong with the transaction.
I decided in the end to go for a larger machine but the 6040 / 6545 machines appear to be good value for money. The only negatives about them to be found on the web are around shipping damage and a few people having minor electronics issues.
I noted that cncdiy seem to be good at follow-up / service based on reading their forums and some comments here..
( Just my 2c worth, I didn't buy one in the end and others will have more direct experience, I've only ever had email conversations with cncdiy, I'm not affiliated etc etc etc. )