My first authentic bag was my baby- my Gucci satchel I bought in 1987 at the Guci boutique on the Via Veneto in Rome. Still have her, never will give her up.
When: about 20 years ago
what: LV noe
where: London
I bought it myself. I don't still have it -- it was in my trunk holding cds and my son asked to give it to his girlfriend about 8 years ago.
if by first "designer" you mean gucci, prada, chanel, lv, etc. then the first one i ever bought would be my gucci tote in classic gg fabric with red/green webbing and leather trim. i just bought that this year (i'm 31 years old) it was HKD 2,500 (so around USD 325). i got it from the gucci boutique in the landmark (central). i still have it up to now and love it to pieces! the other one is a vintage gucci clutch from my mom. i don't know how much she got it for and when. she just passed it on to me 3 years ago. i plan to hand it over to my daughter when i'm too old to care about bags. hehehe.
I got my first high end bag 2 years ago on Christmas. It was a speedy 30 from my mom and I remember it being 545. I was 17 at the time. I still have it and love it. I love LV, but even if I didn't couldn't get rid of a bag from my mommy.
I got my first small signature coach bag (only $120 or something) for Christmas when I was 16. Then the next year spent my graduation money on the Louis Vuitton cherry blossom pochette (around $450?). I love cherry blossoms! I regret not getting the papillon though. And that's where it the obsession started.
I've had Coaches before and an LV Speedy given to me as a wedding gift, but my first very-own purchase of a high-end bag was a Prada leather doctor frame bag, bought earlier this year at the age of 31!