Not worrying about a Pure Sine inverter is insane.
No idea what prices you are using but a simple search on Amazon finds a 2k PSW for ~$200. I use MicroSolar, ya it may be a generic but is perfect sine wave (as checked on O-scope) and rock stable voltages.
A standard inverter (MSW) is good for:
Non sensitive electronics, like power tools.
Blowing up everything else.
Thats pretty much the end of the list. Oh wait, if there is a built in USB plug its ok to charge phones on.
What a Pure Sine Inverter is good for:
Everything.
Plug in a laptop to a MSW inverter and feel how hot the brick gets. Mac's have been known to blow up instantly, or just not work at all.
MSW inverters use MORE power to accomplish the same task. What would take 200w on an MSW would take ~160w on a PSW (these are estimates, as it depends on device used)
This video explains a lot : https://www.youtube.com/watch?v=wimTJw_Gpgk
Lastly, if blowing things up seems unlikely to you, then save the $ and get an MSW. My 2k PSW was about $50 more than a like MSW. That Macbook power brick is $80.
Lastly... there is a negligible standby power drain difference between a 300w PSW inverter and a 2000w PSW inverter, maybe 0.5a.
Also the closer you are to the inverters max power rating, the less efficient it becomes. This is worse in a MSW as the 'wave' gets more corrupted. You are better off having a larger inverter to run a smaller load than a smaller inverter and maxing it out.
Lastly, Voltage on an MSW cycles from 80-140 volts typically as the wave is corrupted, and the 0 point is variable. The Hz cycles as much as 5 Hz as well. A PSW is consistent and has a pure wave. The 0 point is stable.