Assigning the value of ${ENVTYPE}_Var to ScriptVar

I need assistance getting the following to work either using weblogic Scripting Tool, KSH, PERL.
We have an env variable called ENVTYPE. The Variable is used to define the type of server we are on.
Example:
On the test servers, ENVTYPE=TEST
On the QA servers, ENVTYPE=QA
On the Prod Servers, ENVTYPE=PROD

I created an application property file contains something like this:

TEST_Var=foo
QA_Var=bar
PROD_Var=foobar

Could someone please help me with this?

My script sources the property file and then needs to assign the correct value to the variable ${ScriptVar}.

example:
ScriptVar=${ENVTYPE}_Var
print "You are on: ${ScriptVar}"
The results would be as follows:
When ran on a Test server "You are on: foo"
When ran on a QA server "You are on: bar"
When ran on a Prod server "You are on: foobar"

Could someone please help me with this?