i literally just have an HP laptop and a Mac desktop lol. I really do want to get into this stuff though. i bought my first litecoin the other day lol. but maybe ill ask my Dad to invest some cash into this for me .
If you really want to get into it, I would suggest going to PCpartpicker and picking out a MB, CPU, RAM, a couple of GPUs (ATI/AMD) and a PSU to make sure you have enough power. If it is going to be a dedicated rig for mining, you can save money on the MB, RAM and CPU, but not the GPUs or the PSU. This is if your desktop cannot take upgraded parts.
I only got into this because my previous PC was 7yrs old and it was time for a new build. Also remember that power isn't free and explain to your parents that the power bill will go up depending on how much power the rig draws.