You might take a look at the Linkwitz Orion (http://www.linkwitzlab.com/index.html). Siegfried has done all the critical design work, you need to assemble parts & build the cabinets...or just order a premade set. Note that the Orion is an active speaker, though the amp he suggests isn't expensive.
There are a few tried & true DIY recipes out there if you look around. I'd avoid just buying good components & assume they'll sound good together. Much like photography, a great photo (finished speaker) doesn't necessarily require an expensive camera (pricey drivers)...it's what you do with the tools that really matters.
And then there's the resale value...well known DIY recipes may have some demand while unique designs will probably have little resale value beyond used parts.
There are a few tried & true DIY recipes out there if you look around. I'd avoid just buying good components & assume they'll sound good together. Much like photography, a great photo (finished speaker) doesn't necessarily require an expensive camera (pricey drivers)...it's what you do with the tools that really matters.
And then there's the resale value...well known DIY recipes may have some demand while unique designs will probably have little resale value beyond used parts.