I had been totally indifferent to Macs a long time. But since I started working as a iOS developer recently, I discovered that the Macbooks are extremely well designed machines (IMHO)!! I am regularly employed, so I have a brandnew Macbook Pro at work, which I do not use at home.
So being in the same dilemma as you, I bought myself a used 4 year old Macbook (without the pro) which is in very good shape. It was rather slow, so I bought a 250GB SSD drive. Now the machine runs really fast and I am having a great time using it.
It does have quite little RAM, so I will eventually upgrade that, too. But right now, I do not notice that in everyday use, so I am not in a hurry. I can buy the RAM used from people who upgraded their own laptops quite cheap.
The Macbook cost me 500 € and I intend to use it for the next 2-3 years, maybe 4, reselling it later should be possible. :)
(changing the parts is very easy, you can look everything up on the ifixit website, however I did have some experience like assembling my own desktop machines, etc.)
Hope this helps!!