In my case (!?), building one was the cheapest option; the ply cost bugger-all - 1 sheet of 3ply @ about $21/sheet, scrap timber was used for bracing and sides and I picked up an unfinished roll of vinyl off eBay for pennies. The major cost was the form fitted foam insert but even that wasn't especially expensive from your friendly local rubber shop! I used a sound proofing type foam rubber that is quite dense and easily workable, and cost - from memory, about $25.
Hell, yes, it's heavy! But not unmanageable.
By contrast, the cheapest case I could find to fit my pointies was the Gator Extreme with the movable internal blocks which was eye-wateringly expensive and not available in Australia at the time!
However, yes; if your guitar is not a weirdo shape, then a generic case will be cheaper than building one...