I've always found washburn make good quality instruments for the money. More or less any modern guitar you can buy will last you a lifetime if you look after it.

I've still got the 3/4 classical I started on 22 years ago, and it cost my parents $70. It is very unlikely that you'll find THE guitar that lasts you forever - but you might get lucky. I think I'm still looking, but I don't know what for...