distance mesurement using ultrasounds

Hello!
i want to bould a device that can mesure the distance between it and something that it is in front of it, like a wall or any other thing.
basically it is a sonar.
i want it to be based on ultrasounds.
i want to display the distance on a 3 digit 7-segment display, directly in centimeters. it would be nice if it could use a PIC16F84 uC, because i have a few of these. but any microcontroller from the PIC family would be great.
but, here is what problem i have.
i can't find any ultrasonic emitters or receivers here.
maybe there is an aleternative for this?
i hope someone can help me.
thanks in advance!

i found this circuit wich seems to be what i want
**broken link removed**
but i can't find the transmitter and receiver for the ultrasounds. maybe i could use some replacements?
this circuit is temperature compensated. i just need an adjustment for 25 degrees. so no need to make it so complicated.

Ultrasonic sensor sets: www.jameco.com
pn 136653eh $6.95 usd
or pn 1399491eh same price web page will show specs

nope. i can't buy from abroad.
what i wanted was some similar devices i could use.

Years ago, when I was in the electronic security business, We used ultrasonic motion detectors..They had transmitter/recv transducer pairs in them.. I haven't seen one in a while , most now use ir or ir/microwave pair now..Ultrasonics were prone to false alarms from air movement from heat/air systems, neighbors squeeking floors etc.. You might locate one of these and scavage the transducers..