The minimum thickness for 4 layers using our standard processing route is given in the Manufacturing Specifications as 0.8mm:

https://easyeda.com/Doc/Tutorial/PCBOrder.htm

However, we may be able to supply you thinner boards from an alternative fabrication process.

...we are US college, do you offer formal quote and accept the purchase order?

I am not sure I understand the question. Is there some reason your college can not use the online quotation and email confirmation that you will get in response submitting an PCB design using the EasyEDA online PCB order tool which you reach when you click the Fabrication Output... icon (the Order Button) on the top toolbar when you have finished your PCB design?

You can also submit Gerbers for PCB manufacture even if they do not come from EasyEDA.

Please see PCB Order from Order Link also in:

https://easyeda.com/Doc/Tutorial/PCBOrder.htm

Well, the formal quotation is necessary to place a purchase order.
Can you offer that and do you accept purcshase order from college?

We don't mind who orders, we just care where are you, some places we can't ship. From your quote, I am sure you can place that order.

@Estcly,

I can confirm that we can supply 4 layer PCBs with a thickness of less than 0.8mm.

Just select it from the drop down list of available thicknesses and the quoted price will update to show you the new price.

May I suggest that if you require a formal quote,

in Chrome: right click on the PCB Order page and select Print;

in Firefox: open the upper right Settings menu and select Print;

then you set up the format and whether you want to print directly to paper or save/print to pdf and print later.

(Hint: this is easier in Chrome/Chromium.)

If you need any further help, please send an email to support@easyeda.com

Please also see:

Get an Invoice After PCB Order

in:

https://beta.easyeda.com/Doc/Tutorial/new.htm#What-is-new-in-the-V3-2-X