I have an account in steam but it is not my main I was planing in using it to buy the silver starter pack then transfer it to my main account. is it possible?
Not usually, no.
You could try and file a support ticket, asking for the items/time/stuff to be transfered, but this is no gauruntee.
Steam sometimes has things on sale, and PLEX is in my own countrys prices so it is cheaper for me to buy stuff like PLEX in steam, but with that, comes consequences.
Items in the pack will be delivered to redeeming for the account that purchased the starter pack. Some items like skill points will automatically be applied to the character that redeems the item, some like PLEX can be sold or transferred.
The starter packs are sold directly by CCP and other resellers https://secure.eveonline.com/etc.aspx - won’t help much if Steam is having a sale but any sales will likely be offered through other resellers though not necessarily at the same time.