I got my first adult bike when I was sixteen, and it meant using all my childhood savings: first communion money, Xmas money, pocket money from the Aunt in America that comes every 4 years... So obviously the purchasing decision took longer, in my case about 6 months. I even had to change target model twice, because in the meantime some increased the price and got out of reach.
My parents promised me they would "buy me a bike", but they would pay for the basic model in the bike shop. No crappy supermarket stuff, but definitely no XT. In that case it was an entry level Diamond Back (Topanga?) with Shimano 100 GX. I would have to pay the difference to whatever I wanted, which in the end was a Trek 950 (I wanted the 970 but it was another year in savings).
I am glad they did that, as I learnt the value of money and what you get in return. So since then I am much more careful with my money and rarely do impulsive purchases. And the ones I've made end up as mistakes in a huge percentage of cases...