You can lose the weight, but you have to be consistent
The first thing you should do is seek the advice of your doctor. Once he's cleared you for a fitness program, only then should you start.
It's possible for someone so heavy to lose weight. Your biggest challenge will be being consistent in your diet and exercise programs. It doesn't have to take a lot of money to lose weight since you mention that you don't have much of it.
You don't have to buy fancy food, or join an expensive gym. You can lose weight by eating a balanced diet consisting of a variety of healthy foods. Start making healthier food choices, for example, eating chicken and fish instead of red meat, making a switch from whole milk to lowfat, and eventually skim. Start eating whole grains like whole wheat breads instead of white. Steer clear of sugary soft drinks. Instead, drink plenty of water.
You should also incorporate legumes and nuts into your diet as well. Eat as many fruits and vegetables as you can handle.
As far as exercise goes, you can start with walking. Walk around your block once, and then slowly increase your distance. When you're able to, start jogging around your block. If you don't want to exercise outdoors just yet, the get a stationary bike and go for time. Start with 5 minutes per day, and slowly increase your time until you can do 20 - 30 minutes per day. Buy a cheap pair of light dumbbells also for added strength training that you can do 3 times per week. When you get used to the light dumbbells, you can purchase a slightly heavier set.
The myth is that weight loss is expensive. It doesn't have to be. You don't need all the expensive diet pills, home gyms, gym memberships, personal trainers, etc.
I used two liter bottles, canned items, jug of milk, five pound sacks of flour, and whatever else I could find. You can put them in a bag to add to the weight. I'd extend my arms to my sides, in front of me, behind me, etc...