You are probably going to have to go the P & S route for $300-$400. I looked for a used D90 body at KEH and they have two, EX+ $725 and BGN $665. You are looking at a high end P & S or low end Super Zoom. There are so many P & S cameras out there that there is no way I could honestly recommend one over the other. I would make a list of desired options you require and then go to a website like dpreview.com to compare. They have some really good comparison tools and recommendations. There are hundreds of compact cameras out there that they totally confuse me. Besides my three DSLR's, I have a Canon, Pentax and Kodak point & shoot, that all in the right conditions produce good images. I wish I could be of more help. Good luck!
I just thought of another option to buy you some time. How about renting a camera for your trip? There are several online rental companies that many have used very successfully. If you do a google search they will pop up. A couple that I am aware is borrowlenses.com and lensrental.com. You can rent a D90 for a week for about $150. Its just another option.