I am looking to get into gun building and modification. I want to first try upgrading a spring rifle or shotgun before I move to expensive aeg upgrades or builds. I currently have an old tsd m14 spring rifle, and I am willing to use that if possible. I was also interested in an a&k svd, the 115 dollar one. Any other suggestions out there? The price limit is probably $150, for the gun, and then will add more to the budget over time for parts. Thanks.