Dear Sir/Madame,
                I would like to know how can I translate my auction
website(www.ehala.com) from English to Arabic WITH using a translation
software or a module (NOT by using some  subscription services like
Systran, which charges users with huge sums of money per month or some
other translation service providers which charge us per word)

I would like to know some softwares which I can BUY and integrate it
with my website so users whenever they want they can switch from
English to Arabic interphase.
                               Thankyou

actually for me when i want to translate something from english to
arabic there are sites that offer to translate the english sites to
arabic free of charge !!
this is really true , i do it from here alot <egypt >.
you can try this link
http://link0777.com/Services/targemha/default.aspx where you enter the
site and it translates it into arabic with all of its contenents or
http://www.almisbar.com/salam_trans.html

i think those 2 sites will help u alot if you need to translate free
of charge your site through a link
& i you just want it to be in your site , you can contact any of them
cause they will be cheap & will offer a good service.