you might not need a sub depending on what bookshelf speakers you get near-field such as a computer desk many bookshelf speakers do fine on the low-end without a sub..
depending on considions where you live you might be able to get a killer deal on used bookshelf speakers
I have a number of really nice bookshelf speakers I have gotten for a song used
right now listening to my (hard price to ever beat) Monitor Audio Silver S1 bookshelf speakers i paid $11.25 for these at a thriftstore
in fairness when I got them they looked like this..
after some cleaning (mineral spirits + magic erasers + about 1hr of my time followed by coat of Howards restore a finish) they look like this now.
(also pictured very good NHT SuperZero's (paid $50 for these for the pair, and $10 pr optimus Pro-X44AV and $20 pr DCM Timeframe TF250's)
if you have the deskspace you could use a used/ vintage stereo receiver I'm driving the MA Silvers with this ...OMG I love this SOOO MANY BUTTONS...Kennwood KA-V106R receiver (100WPC) $20
but if you lack space a little t-amp (consider imho getting a nicer one than the lepai) my t-amp is a SMSL SA-S3 I like it came with a very nice 4A liteon powersupply the lepai's on the other hand come with rubbish (imho) 2A power supply that reduces SQ until replaced.
here is the SA-S3