Congratulations on finishing your business plan. There are many routes you can pursue to fill the gap in your funding.
A bank is one alternative. However, they will likely require collateral for a $270,000 loan. Banks tend to be very conservative and will likely look for collateral on the loan, or if not, proven revenue.
Your best bet might be a variety of different sources. In addition to the $30,000 that you're putting in, you may want to try and take on business partners/silent investors who believe in the idea. Speak to family members and friends.
You can also try microloans to cover early operating expenses.
There are lending sites, where everyday people advance loans based on your credit ratings.
You can enter business plan competitions. Although the amount would hardly cover the amount you're looking to raise, my company runs one at http://www.launchtogether.com; there are many others though.
Hope this helps,
http://www.ibovo.com - Site to Find Business Partners & Funding
http://www.launchtogether.com - Free Business Plan Competition