I am basing a lot of the information here on a calculation from a post on swtor.com.
The information tells us that 1.6 Galactic Credits = 1.00 USD. Now let's have some fun in the "Star Wars" world…
How many credits would the average American earn?
In a study, it was stated that the average American working in professional, management, and related jobs earned around $64,220 annually. With that being said, a simple calculation will tell you how many credits you would make in the "Star Wars" world.
All you would need to do is take 64,220 dollars per year and multiply by 1.6 to get your answer. Now get out your handy-dandy calculator to get an answer of 102,742! That is the amount of Galactic Credits that you would receive in a year. Of course, that is assuming that a year is the same time span on a planet in "Star Wars."
But what can you buy in "Star Wars"?
Can you buy an X-Wing?
Let's assume that star-crafts are comparable in price to the vehicles we use in everyday life. Some may consider this strange, but to the characters in "Star Wars", this is everyday life.
Some comparisons we could make: The Millennium Falcon could be considered a Lamborghini in price… Or a maybe a Subaru, since it is so old and is still kicking.
The X-Wing was a craft used by the Rebel Alliance. A rag-tag cell of rebels probably would not be able to pay for high-class rides like other people of the Galaxy.
So let's say that an X-Wing is comparable to a used, worn vehicle… How about 6,000 USD?
6,000 x 1.6 = 9,600 GCS (Galactic Credits).
That is about how much an X-Wing may cost you. Whether you can get Jabba to go lower on your price is between you and him… Not me.
How about defending yourself?
For these numbers, I will look at the GCS price in "Star Wars Battlefront II".
A simple automated blaster pistol, the DH-17, comes in at 550 GCS.
550 GCS x 1 USD / 1.6 GCS = 343.75 USD.
A simple blaster pistol will cost you about 344 dollars.
Maybe you're a farmer who has received news of smugglers in the area looking for your crop to steal and sell. You'd want to find some way to defend yourself, so you'd like to purchase a blaster rifle with a scope. Your choses would be the A280C (commonly used by the Rebel Alliance) or the E-11 (Commonly used by Imperial Stormtroopers). Both blasters' prices are the same at 1,550 GCS.
1550 GCS x 1 USD / 1.6 GCS = 968.75 USD.
You can purchase either of these high-powered rifles for close to 970 USD. However, the people you buy from may have a higher price for their weapons.
Of course, none of these numbers account for trade laws, inflation, or taxes.
There are many other things in the "Star Wars" world that you could get a close calculation for, like food, land, ships, and more. However, a lot of this information isn't given, is vague, or is measured in a separate currency (like spice).