Here is where you have to weigh the options.
1) What is available in Pakistan
If you can't get it, you can't get it.
2) Upgradeability
If you put money into a new or used Phenom system you will run into the problem that you need to then replace nearly everything in order to upgrade. If you are okay with than you can save some money now but have to spend more on a regular basis.
3) Used or New?
Used systems can be cheaper, but at a certain point you will spend more on locating older parts to match the system Server equipment can be a nice alternative, but again, you might find yourself needing a replacement proprietary component that might be difficult to locate a second time.
If you buy into a new platform, you can then upgrade parts of it without having to replace everything. Why I like AMD right now: 4C all the way to 8C/16T on the same platform with newer chips likely available in the future.
4) Do you have any components that you can re-use now, like DDR3, that can make up a significant price difference, but I still think it is better to invest in DDR4 at this point.
Check your retailers out and see if they are carrying Ryzen or the new AM4 Athlons. An alternative to that would be Intel's Pentium G4560 and a cheap motherboard, about as fast, and gives you an upgrade path to an i7.