Will facebook advert increase sales on ebay store has anyone tried this? and has anyone posted a facebook add in a different language
you can try it and my suggestion is building a transfer page so that you can use conversion objective and track your ads. if your audience is from different country especially speak different languages, you'd better setting different languages in ads.
I think you should create a Fanpage for your eBay store first, build content for it. And then run FB Ads for that Fanpage. If you get success, there're much traffic and sales come to you.
I have used FB ads to direct traffic to my ebay storefront in the past. It yielded positive results. Depending on how you do it, you can get some amazing results.