nolvas will not give you the same results, arimidex is estrogen inhibitor, it will prevent testosterone from being aromatised, the end result is no estrogen. nolvadex will only bind to estrogen receptors blocking out the more powerful estrogens from binding, but estrogen will still be in your body and can cause trouble post cycle.
arimidex is worth the price, .25mg/ed will do the job, if used at that dose its not that expensive unless your source is really trying to rip you off.
the average price for arimidex is $4-$6 per mg, and at .25mg that will last you 4 days, not too bad, considering the quality of the cycle it will produce.