Lightspeed POS and Shopify

I have a small brick & mortar store with two locations. My POS vendor is Lightspeed (This is the desktop version of the point of sale from Lightspeed). I would like to move forward with using Shopify as my e-commerce solution for a number of reasons (not limited to the fact that Shopify dominates in the e-commerce arena), but I am struggling to understand how I can synchronize the data (in specific, product inventory) between the two systems. I should mention that I do not want to switch to the Shopify POS because Lightspeed POS is a more mature product and I am not ready to trust my core business - POS - to the cloud.

I have spoken with Shopify & Lightspeed support. This appears to be the only solution:

Unfortunately, the $75.00 (approx) monthly fee is outside my budget, therefore this is not an option I am willing to pursue.

My question - surely someone else has crossed this bridge? I'd be really interested in hearing how you tackled the issue. There must be more options...

At a rudimentary level I feel that the Lightspeed Export to TXT could be married with some level of automation/macro to the Shopify CSV import to create even a basic sync that could be manually performed.