I know you mentioned new construction which there is not a lot of in the Glenside/Willow/Abington area, however there is a new townhome section being built in Ambler (with walking distance to the train and downtown ambler) that I recently came across - It's worth checking out. It's called Station Square. It's priced in the upper 200's/low 300's for 3 bedroom 2.5 bath units with garage.
The other thing I was going to mention is to get a good PITI calculator and input all the info so you know what your monthly payments are going to be taking into consideration the taxes of that area. I know it sounds obvious and silly, but a lot of people don't really factor in taxes until after the fact. Especially in the Glenside/Jenkintown area taxes vary A LOT - glenside tends to be lower, in the 3k range for the price house you're looking for, but once you go down 309 a little bit and into Springfield township area you'll be looking at upwards of 7-8k which will make a huge difference in your payment.
Good luck w your search! :)