one - is this a common problem with climbers, especially boulderers - strong, but not that fit in 'general' terms?
two - is there anything i can do to improve my general/cardiovascualar fitness (think that's the right term) that isn't going to cost too much money? (i'm a skint student...argh).
At the end of the day, if you're not naturally gifted with a decent base level of stamina for routes (meaning you didn't start when you were 5) then it'll be hell to get to a good level and even harder to maintain throughout the year, and then you'll still get your arse kicked by that 10 year old girl who can onsight fr8a+'s with her eyes shut
people do have a natural leaning towards power or stamina
Or by climbing easy slabby bold routes and making excuses for or kidding yourself.