I'm not sure if anyone's mentioned this, so apologies if I'm just repeating anyone, I only skim read the last few posts.
There are lots of aspects to owning a guinea pig (even just one) that will inconvenience you at some point or later. A digestive problem that means you have to force feed, round the clock, 24 hours a day. Waking up every few hours to spend probably a long time trying to get a syringe in the right spot, and get your pig to eat. A hay poke in the eye just before you leave for work that means you have to call in sick and take it to the vet, and then again, spend a long time trying to get the eye drops in when you'd rather be watching TV.
Ending up with a male and female (because no pet store is male/females only. They cannot sex properly, and likely have a mix of both genders) and having a pregnant pig, birthing a few pups and having to spend money on properly sized housing and extra food for the little ones. Oh, and then finding a new home for them, if you decide not to keep them.
Being really sick and the only person in who can top up water and hay, chop vegetables, and spot clean droppings won't be much fun, but as a pet owner, it's your job to work through the headache/nausea/whatever and do what they need doing.
Again, if you're a solo owner, clipping nails on your own is no picnic. I clip both my girls solo, but it's a learning curve, and it's either that, or the financial inconvenience of paying for a vet tech to do it.
My point is, pet ownership isn't about what you want. Hell, I want like six dogs, but I couldn't take care of them all properly, so no dogs for me.
If you want a convenient pet, you need to think more along the lines of hamsters, gerbils and the like. They still require dedicated care, but most find they're easier to care for than cavies. Another suggestion Imight have made is fish, but having never owned fish, for all I know they're more complicated than guinea pigs!