Seriously. I actually wanted to do one of those volunteer for a week trips to Belize. It would cost upward of $6500. That is amazing, almost as much as a quarter's worth of tuition. People at my university tell me a lot of people volunteer abroad and that volunteering abroad makes an application stronger. I never really used to believe them, but I'm wondering how much of an effect that volunteeering abroad can have.
In those cases, you're paying someone else to do all the organizing and legwork for you. Most developing countries are not like the US where volunteering can actually be competitive, there's a lot less bureaucracy. I went to Costa Rica to volunteer for a semester. Because I put in the research time beforehand, I found an organization that would let me volunteer for $15/day -- and that included a bed and three meals, and you're not likely to find a bed and three meals for cheaper than that in the part of CR where I was. I was teaching English in a school that had no English teachers unless volunteers came do do it. When I got there the only volunteer teaching grades 4-6 was not a native English speaker himself. I definitely felt like I got to help out, and I didn't have to pay excessively to do it (unlike a lot of people who get their panties in a wad about paying to volunteer, I did not have the mindset that I was entitled to free room and board for my work). Unfortunately there were issues with the management of my particular location (the overall management of the organization seemed fine) and I decided to quit (I can detail these issues if anyone is curious). For what it's worth, most of the other volunteers had paid voluntourism agencies well over $1000 and were living in the same conditions I was for $450. Do your homework, don't go with a travel agency.
I migrated to a slightly busier town (keep in mind this "busy" town was still a two-road town, neither of them paved) and found several opportunities to help out by networking. I think anyone who is interested in helping out a community, and has at least a basic grasp of the local language, could do it just as easily. You just have to go out every night, meet as many of the locals and local expats (who will probably speak English and have a good idea of what's going on around town, maybe even be in charge of some of the projects) as possible. You have to be genuinely interested in getting to know people and becoming an, albeit temporary, part of the community. If you're good at networking you can easily find yourself plenty of things to do. I came across a school built for farmers' children that needed help because I happened to say something in French at a bar, and the French man who helped run the school happened to be standing nearby. I came across a project to help local women in a bilingual local magazine, there was a description of the project and the email address of the woman who ran the project for those interested. Unfortunately the accommodations I had found (through networking) fell through and I had to leave before I ran out of money.
Anyways, my point is that there are many ways to volunteer abroad for free and considering the number of premeds who willingly spend summers putting in free labor in hospitals and research labs, I'm not sure why volunteering abroad has the reputation for being for the wealthy and privileged. The cost of living in these countries is so low that if you can get a good deal on an airfare, you can spend a couple of months there much cheaper than you could in the US (at least California). Even maintaining a pretty high standard of living (staying in hotels with AC, eating every meal out and drinking in bars every night), you can live much cheaper in Nicaragua, Guatemala, less touristy parts of Costa Rica, Thailand, etc, for much cheaper than you could live in a decent apartment rarely going out at night in San Diego.
I understand that this type of volunteering isn't for everyone, and if you're not comfortable socializing with strangers in your non-native language it might not be easy for you. But I just wanted to put this out there for anyone else who might be interested so that they don't get discouraged. I personally plan to go abroad and volunteer again, using the lessons I've learned from jumping in headfirst the first time. The key is to find a town that's not touristy but attracts some expats and network network network. I'm really interested in doing international work and working with the underserved, and I feel like having travel experience to back up what I'm claiming to be interested in will help me out (just like if you're going to tell interviewers that you want to do medical research, you better have research experience to back that up).