Any bike seen at a department store, such as Walmart, are not considered bikes. in the bicycle world they are considered "Bicycle Shaped Objects" and are not safe to begin with and not fully operational. no matter how much work you put into it it will never be in proper working order. you will spend more to get it working (value of a bike shop bike). this applies to all the bikes even the kids bikes.
Sorry but this is a no go. even if you go to Walmart an adult bike is $150+
Best advice i can give you is:
Stick with brand names (Specialized, Trek, Cannondale, Schwinn 'pre-2009')
$300+ bike at Local Bike Shop. these are mainly entry-level bikes.
$150 and under is a low entry Used 'Brand Name' bike (craigslist, local bike shop-used/rented). and get it tuned up ($40).
If you have an old bike spend about $100 to have it tuned up and basic parts replaced as needed.
Save up until you have enough money to buy a real bike.
Do some research on component brands.