I don't want to come across as insulting, but I'd recommend a different pricing strategy. Instead of focusing on the price, focus on the advantages/differences of Strapfolio versus other themes. What does it do differently? Why did you make it? Sell its simplicity: more features != more value when you're talking about website themes.

But don't reduce the price (yet). I'd be surprised if $30 (or even $40 or $50) would be a barrier to your sales. You don't know yet either, so why lower your price? If it's not worth $50 yet, what can you add to it to make it worth $50?

Incidentally, WooThemes (linked above) will charge $70 to use their portfolio theme, and they sell a whole lot of themes at that price.

How much you think is a good price for this?

Honestly, since a lot of it is built on top of Bootstrap, which probably sped up your development time and would also speed up someone trying to replicate it themselves. I would say closer to the $15-$20 range would make it much more enticing to people who know about those other sites.

I really think that you might want to give it for free in a "Beta phase". Get some traction, add features and design and then charge for it. As said before there are much more robust themes for $10 more.

I'm going to take a counter argument here and say competition is already really high so if you compete on price you are heading toward zero quickly which is a price point that will generate zero revenue. Your alternative could be charging $50 (or more) and trying to optimize your marketing funnel with the goal being to attract those too lazy to search for another word press theme.

Going beyond that, non developers find wordpress to be somewhat difficult to implement, making it easy would generate additional interest.

Its easy to say "lower your price", but that has a probability of not working and simply lowering your revenue/profit.