many people say: porting "farms" cost way to much... but whats much? how can i know how much they are gonna charge me? Lets say I made a game like Prince of persia: sands of time for mobile. And i want to port it just to 12 celphones: 8 nokia, 2 Sony ericsson, 1 LG and 1 Motorola... Thanks

They won't do it for a licensed game like that unless you have a license :P.

The only way to estimate this is to think about how will it take to port the game to the other phones... there's no way to tell also from what you've said. Cellphones uses Brew or J2ME, some of them could work on older/newer versions of these libraries than those you created the game for. Each could need differents assets because of different screen sizes... then the audio is not the same on each phones.

If the gameplay is stable and has no bugs porting a brew game can take from 1 day to 2 weeks (maybe more) if the game was designed for porting plus the time spent in QA. Then if you're using Brew you'll then have to get the Brew Certification which can take a lot of time if you're not on their priority list :P... and might be hard to get if they don't like you. With J2ME you can get many problems with the size of you game because some phones have limits on the JAR sizes.

So if we say that the average non-experienced programmer will be paid 800-900$/week for porting and the average port will most likely take a week... it's 9600$ for the development only... then you'll need QA which you can get usually cheaper but i'd say still about 450$ a week (or about half the price you get programmers)... every QA pass will take experienced testers around 4-7 hours for a complete walkthrough (for a complete game that would take about 1-2 hours to complete normally) so about 72 hours total which is about 2 weeks of work so add 900$... Then maybe add some time for the developpers to fix the bugs and the QA to check again... so you can easily double the totals that were calculated previously so it's now [(9600+900)*2]$ if everything goes smoothly. So we can say that the ports would cost about 21 000$ to the company.

Now add all the assets you'll need... the profits of the company that will port your games... if you're using Brew you should also add certification fees, and you'll have a rough idea of how much this will cost. (Price can vary on the compatibility of the phones... some phones could be compatible or require changes that other phones could need... but I'm talking about if the phones are different)

It all depends on how big is the game and how well it was designed for porting, how different are the phones and how easy it is to change the assets in the game without crashing it. If the game is buggy then it will take a lot more time to port especially if you need to get Brew Certification from NSTL (http://www.nstl.com/logoprogram/qualcomm_logoprogram.asp).

You might also consider the fact that if you want to sell your game (I'm pretty sure you want to sell it or you won't be asking for porting it) you'll most likely get something like 2-3 bucks for each "copy" so you'll need to sell a lot to actually make a few bucks.