If you are searching for cheap electric guitars there is a bunch of alternative out there.
You can buy a cheapest electric guitar from as small as 70 and on that point are a amount of brands making cheapest electric guitar.

Dont drop under 90 on a guitar.

If you are buying your initial electric guitar, I wouldnt urge dropping under 90. Most of these guitars are constructed with very inexpensive materials to bring in the production costs down, thus the retail price. The guitars sound will be compromised with this lower quality and the end will also appear a bit tough.
You will usually see that the guitar strings are the cheapest ones you can purchase, they will sound twangy.
The previous downside of these cheapest electric guitars due to the low build quality is the lastingness. You will be fortunate if you can play it for more than 1 year and not have a problem with the guitar parts. You will end up with a cheapest electric guitar (cheap meaning the quality this time and not the price).
Spend 90-150 on a guitar

My advice is to expend between 90 and 150 on your initial electric guitar. You will get some sound quality at the lower end and nice quality at the upper end.
Electric guitar brands to look out for are the one’s that can be called as cheapest electric guitar. The Epiphone, Vintage and Yamaha are the most popular electric guitars from the above list, the Stagg offers the best value for money in my opinion.

Should I Buy Electric Guitar in a Music Shop or Online?

It is actually up to you, simply my advice would be to purchase one of the cheapest electric guitar. You can do this easily online, and you wont get a shop salesman trying to push whats best for them rather than whats best for you.