There are a lot of BBQ Pit Plans and designs you can draw inspiration from. Some of them are ludicrous and wouldn't fit in an average suburban backyard! (They're for event catering).
But if you want to take another, more realistic step with your love affair with barbeque and get beyond grilling pork chops on a Weber kettle this could be the page for you.
There are a few basic designs of barbecue pit requiring varying degrees of skill to build. Check out this, if you can get oil drum cut in half you've got your self a Pit BBQ.
At the most basic level all that is needed is a hole in the ground, or as in the picture above, a 55 gallon drum cut in half.
That said, an oil drum BBQ pit can be made into something more civilised by anyone who can use a welder.
Next up is something temporary but solid built from heat proof bricks stacked in a logical way.
Then there is the permanent brick structure built as a focal point in your garden - built to last decades maybe by a professional builder.
This is pretty much a hole in the ground lined with stones!
Really it's a wilderness camping solution, but with the addition of a rotisserie or a grill attachment to put joints of meat etc on for direct grilling over a camp fire like this Cameron's Products Camping Pit Grill it works perfectly well anywhere.
Dig a hole a six to twelve inches deep and at least two feet by two feet square. Line it with stones and earth - this is mainly to keep the fire from spreading.
Here is a free tutorial for this basic pit BBQ that should last a few BBQ sessions before it needs rebuilding or you want to build something longer lasting.
Another simple solution, albeit much more robust, is to build a pit BBQ using block-work but without mortar.
Again, it's temporary, but will last entire summer and well beyond without any serious maintenance. Check out the picture on the left. Doesn't look that hard to construct does it?
I have heard that certain types of rock can crack and shatter at high temperatures - something to with having moisture trapped inside.
And here is a video clip of a guy building a DIY BBQ pit very similar to this picture, it's short but you get the gist of how he's doing it.
My own favorite, that I have seen gracing backyards time and again is the bricks and mortar type of construction. I have at leat assisted in the building of several of these. The best thing about this design is that with a little thinking and planning you can customize it quite easily.
There are numerous books at Amazon.com contain some nice barbeque plans for varying levels of competence. The plans in them give dimensions, quantities of materials and order of work, etc.
So if you have some DIY know-how, or you aren't scared of trying, give it a go yourself!