There are a lot of farm games on facebook, google play, apple store... I think you can try to advertise with admob like services, or you can think about making your own game (gamers could buy virtual seeds to win real...). Just an idea...
Thanks guys. Well ,why I want to hunt Google? For example garlic seeds. There are like 100 000 searches a month on Google for it: growing garlic, garlic seeds, ... but on ebay I might only do like 1-2 sales a day.
Well, it all depends upon your budget. If you have a higher budget then you can directly go for Google and Facebook ads. If you do not have a good budget then SEO, social media websites etc can be useful to promote your website with no cost.
Redhits, don't be intimidated by competition. It sells well that's why they are there, right? Go ahead with Ebay first and see what happens, you'll never know until you try. Yes, you can try other marketing channels but it will cost you even more in the long run. SEO, for example, if you want to get any good results, you need to be the top 3. Not to mention, paid ads on top of you and "real SEO" nowadays costs a lot of money per month. So, my suggestion is go ahead with Ebay and see what happens. If it does not work, then move on.