He's still the commander in chief and he could still order the end to the detainment program even if he can't cause the base to be closed. And yet he didn't.
It supposedly cost the Clinton administration some $42 million for a 12 day trip to Africa (http://thecaucus.blogs.nytimes.com/2010/11/05/india-on-200-m...). That same article suggests that today it might cost double or triple the $3.6mm/day for Obama to make a trip. Lets go easy and suggest it's only $5mm per day.
Obama regularly makes trips to various parts of the world for at least a few days. Let's say that for the rest of his presidency he spends ten days less on the road. That's $50mm saved.
That leaves around $1mm per detainee to wind down gitmo. I know it's the government so everything is expensive (especially when the military is concerned) but I don't remember commercial flights costing anywhere near $1mm each. Let's say we fly them first class, that's $20k per person, tops. Add in $50k of cash we just hand to them in a bribe to not hate us forever (foolish I know, but what they hell!) a grand for the travel agent, a couple grand for new clothes and such, and that leaves over $900k for lawyering.
Even if their home countries were to agree to foot the bill for airfare back to their home countries, how are you going to get them to agree to that? You'd need someone to negotiate details. That someone costs money.
Detainees will need to be processed by customs before being released. Custom's officers don't work for free. Do detainees even have their passports? Where are replacement passports going to come from, and who's going to pay for that?
Whatever your views on Guantanamo Bay, to think that it's not going to cost anything is simply naive. That's not to say that sufficiently motivated home countries couldn't pay for it, but it's going to cost someone somewhere.
Except if the home countries won't take them. Or if they will execute them if given the chance.
Nothing in politics (or life, even) is simple, so you might as well start by assuming it's hard and conclude it's simple after you've eliminated all the things that could make it hard, rather than the other way around.
Maybe he could do the same thing he did to fund NATO attack on Libya, reroute Pentagon discretionary funds. I don't know if that's feasible, but I find it funny that he can find ways to do a double backflip to fund things he really really wants to get funded but then just throws it back in our faces on Guantanamo.
I have a vague recollection that Congress actually explicitly prohibited spending money on Guantanamo closure, rather than just neglecting to allocate it. I could be way off, but that would be the difference if so.
To where? No one wants them, not home countries and not stateside prisons. This was well publicized at the time, it's not as simple as a little money to move them. Politics isn't that simple.
Sounds like you're criticizing him for not solving a problem that you fail to even understand. No, he cannot fix this by himself, it requires the cooperation of congress as well as either other countries or other prisons willing to take those who can't be released and he's gotten no cooperation in attempting to close it. The "commander in chief" is not as powerful as you seem to think he is.