Which laptop(s), specifically? They might be easier to upgrade than you think.
When looking at an SSD, there's always a tradeoff in capacity. A 1TB HDD will set you back ~$35. The best you can do capacity-wise in an SSD at that pricepoint is ~120GB (unless you find a really good sale). A budget ~240GB range SSD start around $45, with the "best" (ie fastest) SSDs being more in the $80-$100 range for the same capacity.
What kind of price differences are you looking at? If it's <$50, I'd opt for the SSD off the bat. If it's much more than that (and the laptop can be upgraded), I'd be inclined to take the HDD option and buy an SSD + enclosure.
Switch the SSD in for the HDD, put the HDD in an enclose = external drive.
Say $50 for a halfway decent ~250GB SSD and maybe $10 for a USB3.0 enclosure.