So this is Miraflores skate park in Lima
I've heard there are some spots in Lima, probably like one thing to hit kind of thing, but I'm guessing if you're creative you could come up with some shit. I was only in Lima for 2 days before I started heading down the country. Each main city in Peru is a ten hour bus ride apart. You can hang out in Lima all you want, but if you really want to see the country you get out of Lima basically. Once you start heading out of Lima, you start going way above sea level, most of the country would be hard to breath for most visitors, and to help with elevation it is a long time tradition to eat coca leaves. You take some dried up leaves, maybe roll it up to the size of a cigarette and then fold it in 1/2 and put in your mouth so you absorb all the 14 alkaloids. Coca leaves are really important to South American culture too, they ranged from an offering to an ancient "business card".
The way cocaine came about, a German chemist took coca leaves and did a test to isolate one of the 14 alkaloids. Coca leaves is made up of 14 alkaloids, basically 14 really healthy shit for you. One of the alkaloids obviously has the effects of "cocaine", so he used gasoline, citric acid, and about 7 other different chemicals to extract the cocaine out of the coca leaves, in a process called purification. A man sized garbage bag of coca leaves will give you 1 gram of cocaine after you do the process.
So that should give you an idea of how big the narcotic bases are in the jungles of Peru, Columbia, and Bolivia.
The first time I got to film some skating because I didn't roll with a camera by myself in Lima to the Miraflores park, because the last time I heard about skaters going to Peru was the Es team and they got shot at, it wasn't that long ago. Anyways it was cool but heading south down the country heading to Nasca, to see the Nasca Lines, we stopped in this city called Paracas, damaged by a very large Earthquake in 2007, did a little sesh:
Seriously the only real skating if that is your goal is to search around Lima, I don't think there are any legit shops anymore. It's pretty difficult for anyone to start skating because of the minimum wage is so low, no one is able to pick up a hobby, such as skateboarding. So in places like that who knows how people will react with skaters scuffing up spots, when the wouldn't be able to afford to paint it or some shit like that.
So if you're gonna go to Lima with friends who don't skate, odds are you guys are gonna plan ways to go get to the other parts of the country which will be an adventure, stay in hostels or whatever and go to the ancient sites. You can already tell by youtubing skating in Peru there is basically nothing.
I don't know how long of a trip it is from Lima to Machu Picchu, but it is definitely worth it to see Machu Picchu. I bet if I had more time in Lima with a friend that skates traveling with me we'd find some shit, but it would be pretty hard. If you come up on some ill shit I would definitely say try and film it.
With 4 months I would consider checking out some other countries for sure, you could get pretty close to doing all of South America in 4 months, or most of it. 4 months is a long time, I'd budget on the high end if you get sick, I'm guessing $5000-$10,000 bucks. Do a city tour can be 20 sol maybe, and doing something really gnarly can be 300 sol, I'm pretty sure tickets to Machu Picchu are priced around there. Bus transportation can range from 10-20 sol I think. It could be more, but there are online forums such as ours is skateboarding there are some strictly traveling in Peru and shit like that, i checked out some before I went. Sometimes you can find threads that are specifically your exact question.
But I would seriously start to come up with places you want to go and seeing how much that would cost. But you're not going til January, are you trying to buy your ticket soon?