If you are getting someone to say the script (or yourself !) in-house and want a low-cost recording solution without a professional sound recording setup then I use Audacity with an ordinary microphone from a VOIP headset and a few tweaks. Audacity is a good Open Source digital audio recorder and effects processor.
I use a piece of A4/Letter (80gsm) photocopy/LASER copier paper between your mouth and the microphone. This will de-pop your speech. It makes a dramatic difference. Just hold the paper from the bottom so you can still see over it to read the script on your computer screen but don’t have the paper touch the microphone or your mouth (lips, beard, moustache etc).
Open Audacity and set the project rate to 16000 Hz and the input as 1 (Mono) Input. The input is in the Device toolbar (See View->Toolbar -> Device toolbar to make sure it is displayed).
Have your script visible on the computer screen, the de-popper paper held in one hand between the microphone and your mouth and click the record button.
Wait a few seconds to get the background noise (i.e. allow the microphone to pick up the ambient noise because we need to remove this later) then speak your script at a normal pace. At the end leave a few seconds of silence and then click the stop button.
Now select the starting silence (not your words or any clicks from your mouse button at the very start) and click the option Effect->Noise removal and then click the option button in the noise removal Step 1 of “Get noise profile”. It remembers this so now select ALL the audio and then redo the Effect -> Noise removal and take the defaults and click OK.
If you listen it should now be dead silent between words and phrases that you say.
Now select the silence at the start and use the scissor tool to cut this. Select the end silence and use the scissor tool to cut that. Note that you might see a tiny click at the start and end which is the mouse click when you clicked the Record button. Cut this out as well.
That is about all you need to do. Save this as a Audacity PROJECT and then export it as a 16 bit PCM wav file. Upload this and see if it works for you. If the volume is too low then re-open the Audacity project and use the Effect->Amplify to adjust this and then re-save as a new WAV file.
Other tricks are to use Bass boost effect to give your voice some gravitas or to use pitch controls, though you do risk sounding artificial if you alter it too much.