This prevent me to buy lamps and ballasts from there.

That’s just the way it is, Dor.

That's just the cost to move that thing from where it is to you, not much you can change, other than the postage service...

E-Bay combines finding, paying/money transfer, shipping and even some insurance in one convenient package, just a few mouseclicks actually. That allows them to charge an inflated monopolistic price for their service. You can of course do more homework yourself and save a lot with some less known forwarder/shipper etc.

The main thing is that eBay provides a almost global platform for buying and selling, and for that alone they take a 30% cut. There are cheaper more regional alternatives but you'll need to do a lot more work, or take on more risk.

For example Facebook Marketplace dosen't take a cut but it only designed for in person transactions so there's no built in payment or shipping. You can however make arrangements to ask the seller to ship but if anything goes wrong you have no recourse.

Anyway I found the best way to get around high shipping prices is to just use a forwarder with eBay. It works for US to Canada but for other's you'll have to do your own homework.

Ebay USA international shipping rates have indeed become spectacularly extortionate.  Recently I have changed to using a forwarding service, MyUS.com.  Often sellers will ship free of charge within USA, or for quite a low rate.  The international postage costs charged by MyUS.com are considerably less than Ebay and even if you do have to pay for postage within USA, the total of that + forwarding cost is always far less than Ebay's rate - at least for packages sent to Europe.

Moreover, they will even hold your packages and combine multiples together, and re-ship in a single carton.  A further advantage is that international taxes are paid only on the item value, rather than adding that tax onto the item + post + local tax like Ebay charges.  When combining several packages together, I typically end up with shipping costs typically less than a quarter of what Ebay charges.  You have to pay them a monthly subscription fee, but even with that, the saving is huge - and you can stop and start the subscription whenever you need it.

I saved quite a bit of money skipping the eBay Global Shipping and shipping to a forwarder in the US. US to Canada is pretty straightforward as there are companies that make the daily run from Ontario to New York and back. Lots of Canadian ecommerce companies use a forwarder to ship within the US for cheaper rates, the US to Canada package works to fill the otherwise empty truck on the return trip.

The one I use is fairly reasonable, no subscription, just a $9 flat rate to forward the package from US to Canada (which lets you take advantage of cheap and sometimes free US domestic shipping) along with any import taxes. Heavier items do have a surcharge now but I find unless I'm having something like a cobrahead shipped I don't hit with it.

The other advantage of using a forwarder is you bypass eBay's secretive list on what can't get shipped internationally and you use the more lenient restrictions from the government on what's allowed to be imported. For example there was a while when eBay would reject every HID lamp for international shipment even though you could still buy them while they are still legal for import in Canada.   

Side note: since when does ebay decide on the shipping cost?

I haven't used it in a long time, but i thought the seller just chooses dhl/ups/national post system?