I've built a couple sheds, and just posted a question about the greenhouse I just built. My current shed is 12x16. I built it about 6 years ago. I put in concrete piers and attached my floor framing to that and built on top of that deck. Came out great and surely cost way under 4k. Better yet I think it is built much better than. I was just at Home Depo and saw one of their kits and it had some pretty skimpy framing 2' centers and scaled down lumber. If you have the time I'd build your own.

I agree it could be cheaper.
But 2 questions you need to consider - How skilled are you with power tools, and how long can you wait ( and how many weekends can you give up) untill it gets done.

I have all the time and good handyman skills.

But my question is that, I may save some $$ on materials. But if I add all the costs for the tools, do I really save $$ by DIY? This is going to be an one shot project and I do not see I'll do such a big project any time soon. I've touched my table saw for several years....

Best Investment I've made in a long time!

I think this collection of shed plans is the best investment I've made in a very long time.

You'll get the materials lists, estimated costs, and step-by-step, illustrated instructions to build a truly attractive outbuilding for gardening, storage and more.. great stuff here >>http://bit.ly/ryanshedplan

Here is a link that might be useful: Ryan Shed Plans

Funny that someone with the username "ryanshed" clams that Ryan Shed Plans are the "best investment I've made in a long time." 'Shilling' might be more accurate.... Before you send any money his way, research...and you'll find a huge number of negative reviews claiming it is a scam.

It is.

It's a total scam!!