Use a hex editor to edit your save. Here's a tutorial.
Sorry, I didn't quote anything in my previous post but thank you for politely pointing that out :) I didn't quote anything because 1) I wasn't sure I could even post without an account and 2) the quote would have been quite lengthy. I'm not great with the whole "coding my posts" to make cool links, but I appreciate you taking them time to do that for me.
I hex edited my save today (I'm on PC by the way) and I currently have a max inventory of over 10 million. I'll try to come back and provide a screenshot for proof, but it's already past my bedtime :P The link I provided doesn't seem to be getting around much on the internet so I thought I'd share it here. I also realize I'm a bit late to the party (two months after the last post in here), but this is by far the best solution out there; if you don't consider hex edits cheating.
I hope my comment was useful for you guys. I figured my brief statement and the link were a clear and concise way of relaying the info. Please think of the content over the format before down voting my post into oblivion. I only posted it here to get the info out to you guys.
Happy gaming two legs!