Would I be eligible to buy a single policy even if I am a Dependent on someone else's student visa?
You can buy 2 single policies, if you both have separate student visas. But, you would have to buy a couple policy, in case you are dependent on someone else who is on student visa. Insurers usually price a couple policy at a higher price than 2 singles policies, as couples and families they say, usually have a lot of claims that singles. To take that risk factor into account, the couples policy tends to be more expensive.