Metro is hard to blackride, buses impossible (driver will ask you for tickets) though in both cases some local may offer you the ticket, quite expensive too (1.80TL). Check Izmir website for more details: http://www.izmir.bel.tr/en/Ulasim.asp Find out a bus stop on a map on a web-map then go to the nearest bus stop and ask people which bus goes there. Or ask directly from drivers.
Personal experience: Blackriding the bus is definitely possible. Just walk in with a backpack, so that the bus driver can recognize from the beginning that you are a foreigner and just pass the bus driver without doing anything. In most cases they will not say anything, however one time the bus driver didn't let me go out until I came back to the front entry and paid. So be prepare with a filled Izmir card (which you can buy at any metro station), just in case.
Hospitality exchange community is quite big and also last minute request should work pretty well. Ege University has a large campus in Bornova. Either try the benches or put up a tent in a discrete spot hidden with bushes. Also, there are many members of hospitality networks.
Food in the streets isn't generally expensive, especially simple one.
Not as common and frequented by westerners as Istanbul, Izmir is a good location for busking since you won't probably have so much concurrence from foreigners as from locals. Any good spot with people passing by is good for money but the only one where police won't tell you anything is Kibris sehitleri st, that is actually also the main commercial and most transited pedestrian street that means you can easily make good performance and money. The parks along the sea (behind Kibris) could also be a good alternative for both juggling busking and meet nice people
It is not legal any street performance in the whole city, you need permits that you probably won't get from the municipality and police (Zabita) will probably stop you, ask for your documents and so on almost everywhere (e.g. Konak) except Kibris Sehitleri..Though unless you are Turkish, since NONE of them will ever speak english, unable to communicate they´ll just tell you to stop and won´t fine you nor annoy you more. Without a clear reason in Kibris st that Zabita pass beside you and just watch bad at you without telling you anything, so unless you want to stay for a longer period, change places etc don´t move from there.
Izmir is a big city in south western Turkey
A budget recommendation: Visit Ephesus, you can get there with the train to Selcuk and then switch there to a minibus, together it's about 7TL. Maybe you could also hitchhike there. Now comes the budget trick. The normal entry is about 30TL, but you can easily sneak in on the left side of the main entry if you just walk a little bit back next to the fence until you see a gate which is half of the height from the fence. After that no one cares about you anymore and you can exit after your visit normally as you would have paid. Also if you train parkour or free running, the stones there are probably the best parkour training spot you can find in whole of Turkey.