if laptop cost - $2k
if weekly instalment is $14, the shop earn $1.20 from you every
week over a period of 3 years (52x3 weeks).
possible answer - if you can generate more money with $2k over the
three years at the rate of > $1.20 per week for a minimum period
of 3 years, then go instalment.
possible answer - if you cannot do the above with $2k and
immediately have $2k to spare and is willing to part wif it pay for
the hardware in full.
otherwise the need for the laptop do not seem urgent or great drop
the whole idea and just use it as it is.