I read through your other posts and found that other people had given you some wrong information. Namely, one user told you that you can upgrade to a custom firmware from an official 4.xx firmware. Trust me, you cannot do this.
If you are already upgraded beyond 1.50 (you may have bought your PSP with a higher firmware than 1.50), you have no other choice than to:
A. buy a modchip or
B. use pandora's battery method.
Pandora's battery is much easier for those of us that don't want to physically open the PSP and alter it. The Pandora's battery process will require a PSP, Pandora's Battery, and "Magic" Memory stick.
You can make a pandora's battery by opening your current battery and altering it. The process is actually rather simple, but the downfall is that once you change it, it won't work normally anymore. So, you'll end up buying another battery. I recommend leaving your battery alone and buying a pandora's battery.
In addition to the battery, you must make a "Magic Memory Stick" or MMS. You may either buy a MMS or make one yourself. To make a MMS, you simply load certain files onto your current memory stick, which you may later remove if necessary. Unlike the Pandora's battery, the memory stick is not permanently altered. You can read how to make a MMS HERE
. Download what is in the link on the first post and follow the given instructions.
I found that you can buy both the Pandora's battery and Magic Memory Stick (MMS) HERE
for a decent price. If you want to get to a custom firmware with the least hassle, just buy them both instead of making them yourself. Or you could make your Memory stick into a MMS and just buy the pandora's battery, which is also available on the website i mentioned.
If all of this may seem like too much to handle, it is MUCH easier to buy a PSP on eBay or other online store that is already a custom firmware.
I may consider selling mine, actually. It is 5.00 m33-4 custom firmware, which runs iso,cso,custom programs and n64,ps1,gba,snes,gbc games.
If you are unsure about any of the processes I have mentioned, search for guides or tutorials on google. There are a lot of them. Also youtube has guides that are helpful. Honestly, search google before anywhere else. Remember that many of your questions can be answered through google because I guarantee that someone else has already asked your question somewhere else. That's how I learned how to do the whole process.
Hope this leads you in the right direction.