I want create blog to promote some clickbank ebook. Use standard, simple template example sample, or buy custom design ? sample which will be have better conversion ? custom design is important ?
I don't really think it will matter as long as you pick out a theme that goes well with whatever niche you're trying to market. I have bought a few themes and I have a few free ones. If you're on a tight budget then just find a free one there are a ton of free themes out there that are really awesome! I hope you're using wordpress though. It will convert just about the same either free or bought unless you buy a 5k+ theme from ubd. It's going to be more about your skills to make the conversions. Here are some places to get free themes for wp - woothemes.com and freewpthemes.net peace!
Yes there are lot of free themes available for all the niches. like if you want to promote a product on eczema, Just check out "skin care free wordpress theme" (if you don't get desired results, just tweak the keyword a bit), You will find a lot of free themes which are related to the niche/product you are promoting. This way you will get your desired theme at free of cost.