When I first got my Civic 2 years ago as a 16 year old who didn't know much about cars, I threw out $3,000 and got it anyways.
1 week later, the headgasket and overheating started showing and I didn't have the cash or wanted to ask my parents so knowing nothing other than changing motor oil and coolant, I did research and in changed the headgasket myself.
I can't recall the overall price but you'll need essential tools:
Socket and wrench set (I got a $75 Craftsman set from Kmart)
Torque Wrench ($40)
Breaker Bar ($20)
Haynes Manual ($20)
Gasket set (headgasket, intake manifold gasket, exhaust manifold gasket) ~$100 around
Oil, filter, Coolant, etc; $100
Already had a jack and stands
Rough estimate of tools (that will always be used in other occasions) and parts: $400
Basically around $200 in parts
Align motor to TDC
Drained the oil, coolant, removed the manifolds off the head.
(put headbolts in certain order so you know which thread they came out of)
Using the correct cross pattern to remove the headbolts
Removed head, cleaned it thoroughly, took it to a machine shop that leveled/resurfaced it for $40 overnight.
Rough estimate of labor: $40
Put everything back together re-using the headbolts in the correct order w/ torque wrench, (DONT FORGET THE DOWEL PINS)
Coolant, oil put in, fired it up.
I'm pretty sure that's all that was necessary I mentioned, apologies if there's any misinformation.
The shop costs alone are averaged $600-$900 for a headgasket change.
There are many Headgasket DIY tutorials on Honda-Tech, ClubCivic, all over the internet so Google would be a great companion, check them out.